If this is your first laparoscopy, is this a suspected endo diagnosis?
How old are you?
Do you have chocolate cysts?
The above is very relevant in terms of your likely outlook. I have both conditions and underwent treatment for endo over about 15 years.i spoke with my gynae and was in the best position to conceive. And though you're right that many women are more fertile after a lap, it's not the only way to increase chances. Equally, many women with endo nave conceived with absolutely no issues. Has your gynae specifically said you'll struggle to conceive (I was told this in my early 20s,hence a really harsh treatment regime was opted for).
This issue isn't about your ss. (as an aside, in any relationship, over time what you take as no thanks does become more normal, as it would with your own child, inevitably).
The real conversation that needs to be had at this point is, does he actually want more children, not everyone does and frequently people assume they would without actually discussing.
You also don't say how long you've dated, how long you've lived together. Again that could have a real bearing. As could the impact that your partner believes this will have on his son. Not solely because it's a sibling who would live full-time with his dad, but also the age gap would totally change the dynamics. That is likely to be at least a 7 year age gap. Many parents wouldn't want that for their children.
Your yearning seems to be due to your conditions and imminent lap. That alone, probably isn't a good reason to be ttc.
You may also have to review whether the relationship is for you, if he doesn't want children. Remembering that even if you left you still may never become a mother.
I won't the solo mother route, which was the right decision for me, but it's not for everyone and still there's never a guarantee...