Hi Katie! We're about the same age!

I'll be 21 by the end of the year and trying hard as heck to get in shape by my 21st birthday (vanity confession). I started this to combat fitness/health issues but it seems that vanity is one big motivation for me now :P
Weight has always been a problem for me for as long as I remember

I was marginally overweight in childhood and my relatives were not very nice to me (the Asian family hierarchy is not something to mess with. Sigh)
Eventually my eating habits just got worse over the years but my weight was not piling on fast since I joined a uniformed group in secondary school and even made it to the judo school team in junior college! So like you, my eating pattern was sort of... justified by my physical activity I guess. But I gained so much weight in Junior college, taking my weight category (Women's Heavyweight) as an excuse for far too long.
I hit my highest weight in college, being sedentary but with the same eating habits and I just swelled up to the point that even climbing stairs, chasing after the bus, running for class became so exhausting. I was overweight but fit previously, but I became fat AND unfit! oh man. But now I've put myself on track and I now weight less than when I was 17!
And early congratulations to your wedding in 2018!

You have plenty of time to transform your physique and I have confidence in you!
Let's fight on together!