I am in the exact same situation and so sick of it. Lone parenting isn't an option for me but I would really consider it if it is for you.
Just to give my 2 pence worth, I think because they have been single or not with one person a great length of time, a lot of the men I have dated have built themselves a self sufficient, fully functional, ring fenced, little world prioritising their own work, study, friendships, interests etc.
I'm not sure I'm correct here but have started trying to see things not as the men I've dated fucking me over and changing their minds because they are deceitful or fickle, or they've not liked me, but that they feel they genuinely want a relationship but find it extremely hard to align their little worlds with someone else's and make sacrifices. This can include compromising on logistical factors, seeing themselves as fathers etc.
I have been drawn to them in part because of their intelligence and accomplishment (it's not about money, they're not necessarily enormously successful in a financial sense) as well as seeming decent, interesting and kind, but they have become set in their ways.
Hopefully this view might make me more aware of signs when things start to go wrong earlier, rather than looking for classic red flags such as 'is he showing me enough interest etc.' because you say, those things aren't really the issue. Signs I've ignored previously include multiple prior relationships ending because they can't prioritise the women.
I think this approach will be good for my self esteem as it has taken a battering, thinking I'm not good enough for these nice, smart, normal men and they're just wanting to use me for short term company and sex.
I have just had yet another split too, about half a year with a man who was very keen and promising, and I clicked with straight away. Bit different from yours in that there was, to be fair, a big practical issue coming up but he had said initially he was happy to manage this. He later on realised he could not accept the changes involved (which he had been aware of), so we ended things. Like you and wanting kids, I had let him know immediately that I needed someone who in principle, if we got on well and wanted to progress together, which we both did, would be able to work around this issue. I think genuinely at the time he did but push came to shove, didn't want to sacrifice any of his own little world. As with you, he's definitely not the first to start out loving the idea of being with me only to run out of steam.
What I did ignore and hope for the best for some months is that he started backtracking a bit and saying 'well, it could work but...' quite a bit. I don't regret giving things a go as we got on great and it wasn't that long (he didn't string me along for years) but realistically I could have called it sooner. Sounds like with your ex, you started noticing the signs a year earlier but hoped for the best too.
Sorry for the long essay, just wanted you to know you are not alone in how you are feeling and I hope you meet the right guy soon. You're doing the right things in being up front with your wishes and in seeking therapy, I know it feels like 'what more can I do with therapy' but dating in your 30s can be so demoralising so even if it doesn't find you a solution, it is good for your self esteem 