I'm so sorry this is happening to you.
How long ago did you have the lap done where they removed the endo?
I had severe endo and ovarian cysts for years, and sex was always painful for me, much like you describe. The birth control pill helped me some, but never really alleviated it fully, and it could hurt for hours post-orgasm, even if the orgasm was achieved without penetration.
I had a hysterectomy and for me, it was the best decision. It may be for you, as well, but it won't be as simple as you requesting it and getting it. For insurance, they may want you to try certain treatments first before they approve the hysterectomy. There are new treatments for endo since I've had my hysterectomy that they may want you to try, if you haven't already.
Your doctor may hesitate, based on your age and that you don't have kids, even if you've emphatically stated that you don't want them.
My advice is to continue to see your doctor, even if you think it's pointless. Go on record, over and over, about your pain. Let them know how it's impacting your life.
It may be frustrating - it will be - but try what they suggest. You may find relief in a new treatment. Be open to their suggestions. If they can't find a cause, ask what they suggest to do next.
A hysterectomy should be your last resort. It's not without risk, and in ways both good and bad, it's life altering. There are definitely aspects that are freeing, but it does change so much.
And again, I'm sorry. It shouldn't be this hard, but it is.