It sounds like you’ve been through the wringer and I’m so sorry for your losses - I think it’s inevitable you’re reflecting on what’s important to you now.
I was where you are - we'd been together 7 years and had made it v.clear I wanted marriage. He’d said he did too but nothing happening. Eventually at the 8 year mark just when I'd given up on it happening (and probably because I'd given up), he did propose and we got married shortly after.
Like you I wanted to be married - I wasn’t fussed about the dress / wedding etc. but it felt like an important signifier that we were really committing to each other. I wanted to be his ‘wife’.
BUT, I am and always have earned more than him. I received an inheritance which is now a joint asset. We own a property together which I put a larger deposit down on. We have a kid together. Even without marriage we are committed for life because of our child. But if we split up for any reason, I’m the one that will significantly loose out financially. It can at times make me feel a bit trapped.
So I’d think very carefully about protecting yourself financially - it really might not be in your best interest.
It sounds like he is stringing you along. But it might not be malicious, he might not want marriage, but he might have agreed to keep you happy.
Or he genuinely might be needing a while to warm up to it (that’s definitely the case with my DH, once we’d got married he was fully committed but he dragged his heels getting there!).
Only you know whether you’d rather be single than be with him and not married. But I wonder if there are other ways he could show his commitment to you without you being legally worse off. Not sure what that looks like - but legally changing surnames so they’re the same for example?
Also consider - is it fair of you to make him do something he doesn't want to do, to keep you happy?