Dear Joe,  

The fact of having difficulty with some of the above points is not in itself an indication one way or another as regards your vocation. What will tell you something is the type and degree of difficulty you experience.  

For example, number four mentions the ability to love, to be capable of being married and choosing not to. The fact that you have not yet been in love does not of itself mean much. Some young men have never been in love because they chose not to, this is the case of many priests when they were younger -- since they knew falling in love would put in danger the vocation they thought they might have, they opted to protect their vocation, not date, not go beyond normal friendships, and enter the seminary. That is very logical and very mature. In reality they had fallen in love, but not human love, not with a woman. 

As regards the other points you have to keep I mind your age and temperament. To follow a vocation you do not have to be perfect in all respects, what you need is enough to work with. Unless your shyness, reaction to stress, etc. are pathological (extreme, causing major upheavals...) you will probably be able to work on them over time and improve.  

I encourage you to visit a seminary and speak to the priest in charge of formation to let him get to know you, and ask him for his impressions.  

God bless.