Some people may have mentioned some of these already, but just to be sure, I'll say them myself.
Before I start answering questions, I'd like to address a few things with how you wrote your questions.
Firstly, try to avoid saying things like "transgenders." It sounds much more polite to say transgender people. (Or just trans people if you're cool. )
Secondly, you must know that we aren't necessarily "changing genders" but more of realizing we aren't the genders we're assigned with and changing our bodies to match that. A trans individual is the gender they tell you, despite being pre or post.
Now that that's covered, I'll happily answer.
1. Do you get treated differently by others since you changed genders?
I don't know if you're meaning coming out of the closet, or making the full transition, but as you'll probably be told a lot, the process of the transition doesn't happen overnight. It's a long and painful process that takes years. I started my physical transition in, probably, April or May. Since then, I have been treated drastically differently by everyone. My friends have been nothing less then supportive, but I have come across a few transphobes in my times. As a trans person, I just remember that they are not important to my life and naturally move on with my own life.
2. Have you ever regretted your choice?
After some tough times, I have had thoughts of regretting the start of my transition, but I always know that this is what I truly want. I sometimes get thoughts of living an easier life in the closet, but I know that I would be incredibly unhappy to do that.
3. Has there been any drastic lifestyle changes for you once you swapped genders?
Honestly, my life hasn't changed all that much. It may be different for some people, but I still do about the same thing. I go to school, hang out with my friends, and just do the normal teenage stuff. What has changed though, is my P.E. credit. My principle and I have made a compromise so that I won't have to gain my P.E. credit through a gym class, so that I don't have to share a changing room.
4. How is your romantic life? Do you find it hard to date?
My romantic life has actually and probably had the most drastic change. I'll occasionally get crushes, but then I remember, in this age of society, people still do not want to date anyone that is trans. Either for not being able to have sex, or just them not being able to fathom the idea of real trans people, my crushes have always been crushed by transphobic thoughts like these. At the same time though, I'm pretty thankful for this. When I actually get into a real relationship, I'll know that the person will look passed me being trans and love me for who I truly am.
5. What was it like during your first few days of conversion?
The first few days out of the closet were scary, but I'll never be able to thank my friends enough for standing up for me when I was having to tell everyone.
The first days on my physical transition though, they were gross. Blood draws and drugs that made me feel sick were common, and I was miserable. It's the honest answer, but everyone gets passed it.
6. What was the biggest positive and negative for you?
The biggest positive for me was that I was able to express who I truly was instead of having to be expected to do all the boyish things that I never liked.
The biggest negative is, honestly, just the thought internally that I won't be able to birth kids. Not being able to do normal girl things like having periods and such just makes me feel fake. When I really get sad from these thoughts, I usually just talk to my friends about it and eat ice cream. They always make me feel better.
7. How and or, when did you know that swapping your gender was the right choice to make?
For as long as I can remember, I always felt out of place hanging out with my boy friends, and feeling much more in-place with my girl friends. It wasn't until about 2 years ago that I was actually exposed to the idea of someone being transgender that I found that I was trans, and ever since then, I've just always knew that this was the right path of my life.
It wasn't actually difficult to know, but it was more difficult to be able to accept myself as having to be okay with myself.
I hope I was able to help, and I must thank you for this too. It's always comforting to know that there's people who truly want to know these details and learn, instead of just brushing trans people off as a sickness. So again, thank you.