I had my first lap just over a week ago, and have been diagnosed with endo. I was so happy to finally get a diagnosis.. Especially because, in my pre op assessment, i was told that even if i do have endo, there is only a 50% chance it will show up in the lap. I was convinced, like you, that i would be told nothing was found.
I went to see my gp a few days after my pre op, but he wasn't there so just saw a locum. Turned out the locam was brill. (Far better than my own gp!!) He told me that because i'm having the surgery done by a general gynae surgeon, that's why i may not get any answers. He said if that is the case, then he would strongly advice to research an endometriosis specialist and make an appointment with him/her. It costs a lot of money (we found one and were quoted £180 for an appointment), but then the specialist would write to my gp and ask to be referred back to him on the nhs. So wouldnt have to pay for further treatment etc.
My advice is to try not to be too disheartened by your results. I too went from appendix to ibs to endo etc, like you. And i told them from the start that i thought it was endo. We know our bodies well!!
Look into endo specialists, and if you can afford it, then make an appointment. If you cant, then maybe speak to your gp and see if he will refer you to a specialist. I would never consider this with my go as he's bloody useless!! But sounds like yours agrees with you, so you might get the referral.
Good luck with everything. Stay positive. Xx