OK buddy I'm going to say a couple of things you may not like but it's time someone said it.
First of all, enough with the victim card. It's not helpful and only brings you back to this vicious cycle. What your parents should've done? Growth hormones? Even if you were given, it's hard to know exactly how much impact it would've had. But regardless, it doesn't matter anymore, that's in the past, and you can't do anything about it anymore. It's time to move on, and focus on what you can do right now to improve your life (and there is plenty, even without LL).
2 months isn't enough time to do LL. The lengthening alone takes about 3 months (could be even longer!) and then you're looking at a few more months of recovering (at least). It depends on a couple of factors (like which nail you use) but you should prepare for that. I assume doing it after high school makes a lot more sense then.
If you do that, and then go to collage / university - who is even going to know your pre LL height? Exactly, nobody. Moreover, I imagine you didn't walk with a megaphone to your school shouting your growth plates are closed, right? So you can always say you had a late growth spurt. Given your taller siblings, I'd be surprised if anyone will give this another thought. Another thing you should understand, and it becomes really clear as you get older - people don't really care about you whole that much. Everybody are full with their own insecurities and worry about themselves, not just you.
As for athleticism - no, he's not right about it. If you're not very athletic right now - don't expect to get better after LL, and if you are - you'll likely be athletic after LL as well. You should be prepared to lose some (!!!) athletic ability, but definitely not to the point that you can't be any good or enjoy sports.
As for the pain - I'm not going to tell you it's easy (both physically and mentally). I'd say, for most people - it's bad, but not as bad as you think. You do get pain killers to help, so it's not like you're suffering for many months nonstop. Most of the pain is in the first few weeks from the surgery itself, and then it gets a lot better. If you do run into muscle or nerve pain while lengthening, you're able to slow down to help you deal with it better.
Don't worry about your proportions too much. It's not to be dismissed entirely but it's definitely given a lot more importance (and obsession) pre surgery than it should. You should have a consultation with a doctor and they'll tell you whether they think you should do tibias or femurs. It's typically recommended to do femurs because it recovers faster and better, and you can gain more height. You can measure your wingspan if you're worried about it, but most likely it's fine.
I'll end by saying - LL is complicated and scary! We all felt the same way at some point, but as you learn about the process and about people who went through it - you're going to feel more comfortable with it (or decide it's not for you, which is also fine). If you're serious about changing your life and doing LL, it's time to put on the big boy pants, drop the victim card, and do the research. There is a lot of good information on this forum and on youtube, which is a great start. Good luck!