Pain during sex (female)

So basically i started seeing my new parter around august last year and in about november sex started becoming very painful for me internally. There was no change in the way we did anything and id never had it before, even with my previous boyfriend who was 'better endowed'. It has progressively gotten worse and i've been for examinations, ultrasounds, STI tests, operations to test for endometriosis and the doctors have basically said there isn't a lot more they can do, suggesting it may be psychological, however nothing has changed at all which could cause it to start, i havent had a bad experience with sex that would make me nervous or anything.. Its getting to the point now where sex is becoming impossible for me, where as before it was only positions where he could get deep that i had to avoid.. on a few occasions i've collapsed due to the pain and every time we try now i have to ask him to stop. Also, we thought it may be due to me getting nervous about expecting it to hurt which made it worse but every time we try we make sure im really calm and ready before we try. It doesn't seem to have any correlation with my cycle either.. I was just wondering if there were any other girls that experience this and if anyone knows of any solution. While my partner has been so patient with the whole situation it is starting to put a strain on our relationship!

Many Thanks!