Hi Aina,
Our paths had never crossed up until now but, before making any attempt to react to your posts on this thread, I have just quickly gone through your previous posts. One thing you said made an awful lot of sense to me. You have only one year left in college and, since you consider yourself a bit of a late starter, getting that finished before trying to take anything else on does indeed look like it should be your top priority.
If you have gone through the posts of other people in your age group, you will have noticed that employment is a huge issue for many and without employment it is very difficult to move forward effectively with everything else.
Against that, as quite a few of us can attest, when you have marketable skills, being transgender is not nearly as big a handicap as you might think. If you have been following Joanna Dark's threads you will find a recent very good example of what I mean.
Regarding your nephew, by any standards, unless he is stating clearly that he is a girl, it is probably too early to draw any conclusions. That being said, I do agree with LtL that if the subject comes up in a conversation again, you may be able to use it to open a general discussion on the topic. A good way for you to test the ground.
BTW, based on LtL's experience, among others, if you really think your family would be strongly against your transitioning (supposing it really is something you want to do), I would strongly suggest that you have a back-up plan in place before coming out ie. that if necessary you can move out. To be frank, unless your parents are really very supportive, I'm inclined to believe that trying to transition under the same roof as your family is just inviting trouble. Emotions run too high and between fear of what others will think and feelings of guilt, there is a whole minefield of obstacles to get through.
Right now, use all the threads here, and a couple of LtL's, like this one:
https://www.susans.org/forums/index.php/topic,143167.0.html , are particularly interesting giving the issues you seem to be facing, to help you sort out your own thoughts.
Wishing you all the best.
Donna