Relationship advice!!! mature people only please?? kind of long so bear with me?

Ok so I met this girl a couple of months ago..we started dating and have been for about 3 months now. She is 3 yrs older than me..I'm 21. Before we got together she was kind of hesitant she said she wasn't over her first bf (im her 3rd) and she didn't want to hurt me. Somehow she changed her mind and we ended up being together. Once we got together I asked about her second bf she said they broke up because she was kind of bored and she thought she was over her first but she wasn't. She said her 1st was always on her mind when she was with him but she still dragged the relationship for 9months and finally broke up with him. This has made me extremely insecure. She also said she usually gets bored with guys within 4months. More insecurity. Insert a couple of fights and flash forward to now. She says she loves me as a person and we talk here and there about marriage and stuff. I like her a lot and can see myself with her in the future but I am extremely insecure and don't know when she will get up and walk out on me. I call her and talk to her every chance I get. And I wanna see her whenever I can. she swears she is over her ex. We have had sex but I've been able to not perform a couple of times which I think is performance anxiety. I now feel like she is completely avoiding sexual talk and she doesn't call as much as she used to and when we talk she taunts about the sexual stuff then says she was joking when I get mad about it. i dont want to end the relationship like this i want to prove to her that i can be good in bed like i was before i met her. Can someone tell me what to do...where to take this relationship.. What to expect.. I've unintentionally cut off hanging out with friends it's just usually go to work ..look at my phone a billion times hoping she'd call..then she calls..go home...eat talk to her till she says goodnight..then go to sleep. I don't know what to do...help please I feel like she is losing interest....we dont even kiss the way we used to a couple of weeks ago...and when i want to talk to her about it she says leave it alone..stop annoying me with this ****...blah blah blah..any advice would be helpfulRelationship advice!!! mature people only please?? kind of long so bear with me?
shhRelationship advice!!! mature people only please?? kind of long so bear with me?
communication is key... tell her how you feel. If she doesn't want to talk it may not work.