Instead of using 5, 6, try using "five...six"
There have been more than enough challenges for my family, being Hispanic and undocumented for a few years is really difficult
I think you should take out "is really difficult" or have a period after family
When you state you want to be a physician, it seems a bit abrupt to me. It was just stated and thrown in there.
It kind of seems as though you're stating your last and final goal in life is to become a missionary physician, I hope there's more!
Last bit of advice, try inserting a conclusion, wrapping up everything