One of the interesting things about this reason for thinking you haven't got a vocation is that if we say it right it brings us up against perhaps one of the most puzzling aspects of vocation decisions. Let's say it right.  

"It is a very good and necessary thing to have good Catholic families, so how can there be anything wrong with doing that instead of following a vocation?" 

In other words, there cannot be anything wrong with not following a vocation if what I am doing instead is something good. 

Ready for some deep reflection? 

First we have to get some basic things straight about right and wrong, good and bad. 

absolutes and circumstances 

There are some things that are of themselves absolutely wrong and bad. To gossip and slander your neighbor, for example, ruining his good name by telling lies about him is wrong and should not be done, ever.  

There are other actions that are right or wrong depending on the circumstances and any sane person will deal with them accordingly. Take the action of sending a baseball through the picture-window of your neighbor's house. If the house was on fire and you threw it in order to break the glass and get in and save him he ought to be eternally grateful to you. If you did it out of spite because he beat you at tennis you could rightly expect him to come looking for your hide. If you were playing on the street, took a fast pitch right on the sweet spot and the result was a "homer"(!) right into his front parlor...you would expect him to be mad, but you'd also expect him to quiet down once you apologized and promised to do your best to pay him back.  

omission 

But on top of these there is another kind of wrongness, those things that are wrong by default. It's not that they are wrong in themselves; they are good, but not what they should be, or as good as they should be.  

Suppose you go to a top gourmet restaurant and choose their "famous" hamburger. You naturally expect something extraordinary, yet what you get served up is more like what you would produce on your worst day at the grill at home - just a patty, a slice of onion and a dollop of ketchup on a pretty ordinary bun. You would probably call over the waiter to ask for an explanation. And even if he then cut the price to what you would pay at the local stand, you'd still feel somewhat let down and deceived; after all, this is a six-star restaurant. Yet the waiter could still say, "Tell me what's wrong with it," and you might find it hard to express reasonably what you feel. But you would still know that something was wrong, or at least definitely not right.  

switch 

And then there are things which, though perfect in themselves, are wrong because they take the place of what should be there. Such as when you really want fish, order fish, expect fish, and yet get served meat, even if it is their best filet mignon. It's wonderful, but it's the wrong thing. 

It is the case of someone who does not deliver what he is expected to, even if what he does is good in itself. There is still a defect, it's the "wrongness" of not delivering.  

Now let's take it a little further.  

love again 

There are things we expect from those we love. Some time ago I heard of a pair of twins suing each other. It took a while to absorb that one for, besides it being over something quite trivial that you would expect to be worked out with a little patience, you would in any case expect some further flexibility between twins.  

Why would it seem ridiculous for a father to complain, "Well if Mr. Smith across the road is not going to take my kids to the ballpark and can get away with it I don't see why I should have to?" Because the family relationship based on love should change things. 

Love definitely does make a difference. It changes our expectations, and it changes our duties. Love makes demands like nothing else. Love gives a new content to the words: right, wrong, better, worse. 

new context 

When there is a love relationship involved, these words are no longer determined solely by the materiality of what they are applied to. Once we are beyond the area of things that are absolutely right or wrong in themselves, we have to look at a little more than the materiality of what we are talking about if we want to use the words right and better, and we have to take into consideration the expectations of love.  

what is needed?  

To build the Body of Christ, to spread his Kingdom in this world, Catholic families are undoubtedly needed. Yes, and a lot more. A lot more Catholic families and a lot more than Catholic families.  

What is needed is for each person to find his place. 

the Body, the Mystery 

Perhaps the single greatest error we tend to make in considering the Church is keeping ourselves at the center. We can free ourselves from this to a great degree by referring to St. Paul's comparison of the Church to a body.  

If the foot should say, "Because I am not a hand, I do not belong to the body," that would not make it any less a part of the body. And if the ear should say, "Because I am not an eye, I do not belong to the body," that would not make it any less a part of the body. If the whole body were an eye, where would be the hearing? If the whole body were an ear, where would be the sense of smell? But as it is, God arranged the organs in the body, each one of them, as he chose. (1 Corinthians 12:14-18) 

In God's eyes we each have a different part to play, a role he had in mind when he created and redeemed us, and when he called us. It is Christ's thought on how best we can serve the Church, and so it is an expression of his dual love - love for us in finding the "perfect spot," and love for his Church in providing for its needs and growth through our individual call (some as fathers, some as mothers, some as priests, consecrated lay persons, religious, hermits... each according to his own call).  

vocation to service 

Those whose vocation it is to form Catholic homes and families need the service of those whose vocation it is to consecrate their lives to the Lord. It is perhaps easiest to see their need for a priest's ministerial service, especially in the sacraments of Reconciliation and Eucharist. But they also need the prayers of contemplatives, and the witness of those who leave everything to follow him in religious life and consecrated life, who dedicate the whole of their lives, without distraction, to serving him and making his Kingdom come, serving Catholic families in many apostolates, especially education.  

so, what is needed?  

What is needed is for you to find what Christ has in mind for you.