I've never had a sexual intercourse without pain...[female]

I'm 21, I've been in a relationship with my boyfriend (25) for now 3 years. The problem I have is that every single time there is penetration during sexual intercourse, it hurts. In the worst times, I have to stop everything because I feel like it's tearing me inside. If everything is going "normally", it hurts quite much when he enter in me. Even during masturbation, I can't go more than 2 fingers. Even with lots of lube, it still hurts, like if I was too tight, no matter what...

I already went to see a sexotherapist and she thought it was mostly psychological, because at the time, I stressed a lot with the pain and it was a burden on my sex life. Now, I am more relaxed with it and I try to take my time and simply enjoy everything, but the pain is still there... Any idea what is happening?