Hi OP. I was in a bad marriage until I left when I was mid 30's, and we never had children (pretty soon after saying "I do", I knew I'd made a helluva mistake in marrying my ex husband and wasn't about to compound the issue by having a child with him)...
After I left I spent some time thinking about whether or not having kids was something I wanted moving forwards. Ultimately, the decision for me was that I was 'open' to the idea if I met a really great guy, which didn't happen. At the time, freezing my eggs was something I did look into. In the end, I decided to let things unfold on their own, without any medical intervention, and a couple of years back had a strong sense, can't really describe it, but a sort of 'knowing' that it just wasn't part of my future. I shed a tear or two, quite literally then acceptance rapidly followed.
I'm now almost 42, and personally I feel relieved I've not had them (have since also met a GREAT guy, and the compatibility is there, and he can't stand the little crotch goblins!).
Lots of close friends have had kids late 30's/ early 40's, and as far as I can tell, do not regret their decision, including some who needed medical assiatance. I also have friends who like me, are either no longer interested or have never been interested, and instead are really content to have the benefits of being child free.
It's such an achingly personal choice. What does your gut say?
Just to add, it's totally OK to no longer want them. It sounds like you're perhaps stuck in that uncomfortable limbo land of figuring out whether you want to continue to invest in aiming for something that perhaps isn't as strong a pull, as it once was?
If you were to try IVF and it works, does your instinct tell you that you will feel joy, or have you started to move past that and now envisage a life where you can do things you perhaps wouldn't be able to do with a little one in tow?
None of us who are child free can know if our lives would be 'better', having had one, but what I will say as someone without them, I have no regrets. Love my freedom and hobbies far too much!
That said, I have one friend in particular who initially wasn't ever keen, but her husband wanted them, and mid 30's she felt like it was something she could be open to... she's now got 2 and adores being a mum!
I say listen to what your heart is truly saying here.
Good luck OP xx