You're clearly a guy with high standards - somewhat of a perfectionist, but also somewhat risk-averse. You don't like to settle for what you feel may be second best, but how do you really know if what you have is "second best" or "best"? And how do you know if pass up this opportunity you will get any better in the future?
Sounds like she ticks many boxes logically - your head says "yes", but you're not feeling it in some ways - so your heart says "not sure". Part of you wants to find perfect woman, but you're getting older - and you're not sure if you'd be throwing away something really good.
You seem to be in a similar situation to me in some ways, give or take a few bullet points - see my post
relationships/amazing-girlfriend-but-ca ... 98300.html - please correct me if I'm wrong
Here's a few things I've been thinking about so far.
I'm a scientific thinker and I like to solve my problems logically, sometimes maybe too logically
Have you read about this?
https://en.wikipedia.org/wiki/Secretary_problem
That page goes into a lot of math and detail, but basically it describes meeting people one at a time, and how long do you reject people for before you should settle and be confident you've had the best probability of settling on the best person.
How much time did you spend dating women before you met her? Is she better than all the women you were with before her? How much time would you be willing to spend in future dating to find someone "better"?
What about the women who rejected you before you met her? Do you feel you have the ability and willingness and time to improve yourself so that you're able to fish from a better pool of women? If so, then that kinda invalidates the "secretary problem" to an extent, because you'll have better choices available to you in the future. There's always the risk that you won't improve tho, and won't be able to attract women more like your ideal - it's a risk to go down that road no doubt.
There were a lot of things I didn't do in the past in terms of pickup stuff and skills with women, so I feel like maybe if I tried different tactics in the future I would end up with a better pool of women to choose from.
Also, another thing I've been grappling with is, are a lot of her good qualities because she loves you so much? From the way you speak, it sounds like you might be a little bit "above" her in some respects, perhaps above her in looks. If that's the case, does she see you as such a great catch that she's willing to do anything for you? If you met a hotter women with more options, would she be as committed and as compliant as your current girlfriend?
As I said, it feels like you're in a pretty similar situation to me, and the above is some of what I've been considering. Please correct me if I'm wrong though! Hopefully, you will find some of this useful...