Hi Eemie
I have stage 4 endometriosis and PCOS and the pain has been worse than labour. Not sure if I can get pg again (DS conceived on Clomid, periods returned after 6 months with a vengeance, despite breastfeeding).
If you do have a hyst, you need to get rid of the ovaries too since that's the trigger for the endometriosis (from what I've read, people who've had hysts and have even a fragment left can still get the pain).
Who did your surgery? If feasible for you geographically, can I recommend Mr Robert Richardson at Chelsea & Westminster (and I think a hospital in Guildford)? He's done two laseroscopies on me - before the first he said he'd give me five years clear, after the first he said he hoped it would be two and said he'd never seen such a mess (I tend to make light of pain and he didn't realise how bad it was from talking to me before the surgery). I went 23 months between surgeries and conceived DS 11 months later.
this is a link to the Oxegene study which is seeking to discover whether there is a hereditary link with endometriosis. FWIW, I think there may well be, but I also think there's a strong immune system link too - I know my immune system's not great and it seems that a lot of people have the 'retrograde menstruation' that has been blamed for endo (The Telegraph had an article a few years ago about how it was wearing tight trousers that caused it because women in India didn't get it as much (FFS!!! Like that's the only difference?!!).
I'd be inclined to give the GnRH a try first, but having said that I don't react well to drugs, so maybe I wouldn't. I did take Provera (not GnRH, obv) and it made me bleed for over a month and made me think psychotic thoughts...!
HTH a bit hun. Hugs for the pain - I know how vile it is. xxxxxx