A laproscopy sounds like a good next step to me... you'd know for certain if there were any signs of it.
Reading your post was like reading my experience too. I'm not even 'allowed' a laproscopy nevermind any ops to get rid of anything... although I wouldn't want to be infertile. I used to really love the idea of having kids, I 'knew' it'd happen, now I'm not sure that day will come, but I'd hate to want to and not be able to.

Anyway... I used to get violently sick with the pain too, I even ended up in hospital a couple of times (and still they ouldn't do anything... "too young" they said... I'm 20 too by the way) I still suffer through the pain, but it's less often now as I've been put on a progesterone only pill (Cerazette). It was awful the first 6 month, I still got horrendous pain and heavy periods (a lot more often actually) but it was worth it in the end. Now I don't have periods at all (except recently when I lost someone and went through a REALLY tough time, think the depression and stress had an effect on that) and the pain has eased quite a lot... I still get it sometimes, but nowhere near as often.
So yeh... Cerazette (or the depo injection) and a laproscopy might be worth a go...

I'm sorry you're having such a hard time too... I hope it works out for you. Let us know how things go?
Take care,
Molly