You are 15?
You are very intuitive knowing that you have been a pushover.
Try researching being a "pleaser' and see if any of that fits for you.
Also, if you are up for some self challenges, research people like Jim Rohn, Zig Ziglar and Anthony Robbins (they are all motivation speakers but its the self assessment challenges I am interested in you taking).
I know all too well how it feels to have everyone tell you that you can't do this or shouldn't do that...and if you stick up for yourself you get crap for that too.
Don't become an a$$hole, but there are plenty of reasons to stand your ground and dont let these folks push you around.
But be careful and choose your battles...and make sure you are standing up for what is true and just and right. It's lonely doing the right thing and standing up for yourself.
Eventually you will fall in with the kind of people you NEED in your life and then it will all make sense.
Be brave and do your own due dilligence..self assess, self challenge, self improve; Your confidence will skyrocket and you will thank yourself when you are my age