Hi Lucky Wishbone, maybe this isn't anywhere near as much about you being mentally slower or less mature........maybe this is much more about the way you feel around others that's effecting the way you act.
You mentioned feeling pressured by some people........well maybe it's them to blame if they're behaving in an "intimidating" way towards you or/and maybe it's more about you not feeling confident. And leading on, maybe it's a case of you having lower self esteem (especially if this has been happening "my mom shouts at me angrily afterwards what I've done wrong") and having difficulties expressing yourself at your level with other people.
And naturally depression is going to effect how well you're able to communicate with others.
So if you get where I'm coming from..........depression, anxiety, low confidence, low self esteem............do not need to mean that you're "mentally slower" or less mature. Plenty of really smart, really mature, amazing (!!) people can still experience the effects of any of these. It just may mean that you need a bit of help in overcoming these.
And you've got to remember that even really smart, really mature people can sometimes, occasionally behave in a "childish" manner, especially when they are with people they feel comfortable with......it can be as much about just temporarily being able to/comfortable enough "let go"/cut loose of the "should"'s.........so maybe that's where the "accidentally" bit you mentioned fits in.........the thing is just to try not to let it lead to hurting others.
And just be careful how far you go to trying to "live normally........like other teenagers"............sure there might be some "norms" you need to follow, but there doesn't have to be anything wrong with some differences either, in fact some differences can be really good!!!
So, it really is admirable that you're wanting to work on things you find difficult.......and go for it!!! But if there are certain areas that are more a reflection of you as a person/who you are, it's much more important to be yourself and to be comfortable with who you are, and there will be people who are going to respect your individuality.
Just some thoughts...........

Alison