Dear Tara, 

You are now 30 and you have behind you the experience of trying religious life and being told to take some time outside the convent. The result is a continued desire to live religious life, although mixed with fears which have to do with your health, the possibility you may again be told not to continue, and fear of upsetting your father.  

Start by eliminating the least important. If you are 30 and what you want to do is good, your father's reaction is the least important to worry about.  

The other two fears should be addressed and settled by speaking to the vocation director or superiors of the congregation you are thinking of joining. Ask them what they think. I imagine you have stayed in touch with them, so they should be able to give you concrete advice. If they do not think you should join their group, ask them if they think you have a vocation at all and if you should look into some other order, or if they think your call is to the lay state. Then take them at their word and go on what they say. If they have doubts you can safely conclude your vocation is to the lay state.  

Don't forget to pray and offer yourself to God, and ask him for the fortitude to accept whatever it is he wants you to do.