I don't think endometriosis will cause chemical pregnancies. Endometriosis is the migration of cells that ordinarily stay in the uterus, to other areas in the abdomen, where they swell and hurt when affected by the hormone flow during your period. They are painful and annoying and presumably can also cause scar tissue if there is internal bleeding, but none of that would affect an egg or embryo such that a chemical pregnancy results. When did you have the chemical pregnancies, were they within the last few years? You might simply be dealing with time, affecting egg quality as it inevitably does.
Having endometriosis can complicate things when it comes to TTC. I'm a prime example. Had the laparoscopy and a hysteroscopy in june 2010 and I've been TTC for 8 yrs!! BUT I have horrible periods and heavy bleeding.. SO those 2 on top of being unable to conceive they naturally did the surgery. They found endometriosis, a cyst on my fallopian tube and a polyp in the middle of my uterus. I'm praying after having this removed it will help but it's been 8 months now and nothing :(. I honestly don't think they removed all of mine. :( Anyways, I wish you both the best either way!! Good luck! :)
I am in the exact same boat as you. I have NEVER been officially confirmed with endo although they suspect I may have it since my mom did. They also told me it didn't matter when doing IVF. I have done 4 IVF's & had 1 chemical, 1 blighted & 2 BFN.
If you are having multiple chemical pregnancies I would think it's just a matter of getting a good egg. I am 39 (as of last week- UGH) and will have transfer this weekend with donor egg.