How do you deal with a slightly selfish stubborn 18 year old girlfriend??

I have been dating this girl for almost 2 years...im 20 and shes 18 and she was an awesome girlfriend for the honeymoon months but then shes changed she will not open up to me for anything...she wants me to open up to her but when I do I get her mad and she tells me im complaining and tells me to stop...everything has to be her way now a days she controls the way I drive...she gets mad when I go to the bathroom and says I go to much and need to hold it bc it makes her look stupid waiting for me...I love the girl to death she gave me her virginity and I hold that very close to me and lately even sex is boring its always what she wants to do and it ALWAYS involves me doing all the work and she never wants foreplay anymore...and I don't know if its just me but se seems to go to the bathroom right before we do it I don't know though...when I tell her were falling apart or maybe we should break up she gets mad and tells me to do what I want...she doesnt even try to stop me, as far as I know im her first love...and she still will just let me go...she gets mad at me when I cant think of somthing to do and when I cant continue a conversation after already talking for 3 hours...our phone talks usually end in an arguement...a dn I dont want to end this relationship but I just dont know what to do anymore...I've tried so many things and finalluy I quit being nice about it and told her truly how she makes me feel and I didnt sugar coat it a bit...shes become a bitcy girlfriend and we arent even married...the thought of her being owoth another guy hurts a lot..I cant control her life but still...I just dont know how to save it, right now we arent talking bc I told her I need time to think after once again she got mad...maybe it is all my fault I don't know. I don't know how I am trying to save a relationship but still get made out to be the bad guy...anyways..thanks for reading and advice would be great,,,but it prolli confuses you to
thanks for any help

Every relationship is different and I dont know the two of you well enough to be able to say exactly what it could be but I can tell you this

Im eighteen and im in a relationship with a 21 year old...we went through something similar...I had a certain way I liked things and I wanted them to be done that way I would get mad when he would drive too fast or when he wouldnt do something I asked him to do and to this day I dont know why I couldnt get over stupid stuff like that...at the beg. of a relationship its like anything can change its ok cause were head over heals and everything is up in the clouds...then reality sets in and we want our life back but we dont want to lose this wonderful new addition (I say we as in like other eighteen year old girls lol) so it becomes hard to have both we dont want to change but we dont want to lose you and when we get 'threats' (take that term lightly I couldnt think of another word to use) of our guy leaving...we freak and think 'well fine if they can get rid of me that easily then just go' its like in our minds its all or nothing we dont want to get married but we dont want you to leave...sometimes you both just have to scream at each other...just get everything out..even the most of trivial things
my boyfriend and I had to seriously sit there and say 'this bugs me and why do you have to do that and I cant stand this and change that' and then at the end you have to realize what can and cannot be comprimised ...for example: I hate that my boyfriend drives way over the speed limit cause I dont feel safe...but my boyfriend hates the fact that I turn the music up real loud...so we had a talk and I said I wouldnt turn the music up to the point wher eit was shaking the mirrors and he wouldnt drive to get us killed and after that its just who evers car it is is the one that makes the rules...its just stuff that you have to figure out but you cant do that without talking and a lot of the time talking will end up in yelling but dont hang up the phone whe that happens and dont just leave just get it out both of you just need to get it all out and hopefully at the end you both wil have a clear mind and will be able to comprimise on your issues and youll both be able to see what is in your relationship

im sorry that was a really long answer but I hope it helps!

Best of luck to both of you