I have a different belief

I don't think YOU made any decisions about where you were born etc. However I do think that wherever your past lives come from (reincarnateion, second souls, whatever) that they have the ability to affect you as a person. This could be as you suggest, a guilty conscience or simply a wishing to help those injured on a spiritual level rather than physical (which could explain the apparently random nature with which you distribute your help)

One of my other beliefs is that while we have no strict destiny, we are guided along a certain path by the gods (or angels on behalf of the gods more often) and that they can only point the way, perhaps the people you feel most for are physically disfigured, leading you to a job in plastic surgery, leading you to make such a difference to peoples lives who have been given horrific injures.
This is only an example, and I must state this, DO NOT LOOK FOR IT! it sounds daft, but the gods will only choose people who will want to or be able to accomplish these tasks. If you keep looking for your 'destiny' and diving head long towards every 'sign' you will miss it. Live your life, do what you enjoy, and the gods will guide you to the doors they wants you to go through (if indeed they do have plans for you :P)

Finally, and I have to say this, maybe your just knakerd? being a med student is tiring, and not everything is a test from god, he wants you to live aswell!

If you think something spiritual is behind it, then meditate on the subject and maybe you will find the answers you are looking for, if indeed you are asking questions they can answer!