There are tons of theories about how endo decreases fertility, in cases where it hasn't caused structural problems. We talked early in this thread about how the most common theories have to do with inflammation interfering with implantation. I'm not sure about egg quality issues.
I did a bit of searching, and what I found was specific about endo that's found inside the ovaries. I'm not sure if endo would have an effect on egg quality if it's only in the abdomen.
I think the NK cells are potentially an issue with endo women, but I'm not really sure.
But, I'm not sure anyone really knows. I think there are a lot of unresolved questions about endo.
As for the lap, my doctor told me that an additional 1 in 12 women with endometriosis will get pregnant following the lap compared with endo women who didn't get it. I'm not sure if that's in 6 or 12 months. So there's a positive effect, but it's small. That's, of course, in addition to whatever % of those 12 women would get pregnant in that time anyway.
Unlucky, I'm sorry your IVF didn't work.
Yearning, I hope you get a bfp soon.
8long, sorry I don't know anything about progesterone and immune issues.