I am maxing out my TSP, with plans to max my HSA contributions during my next pay raise, but I'm wondering if dialing that back a bit so I can finally buy a house makes sense.
In short, "no."
It might be "yes" if you would ask this question after you have been married for at least a year, and have lived for at least a year in a city in which you expect to spend another ~5 years or more. Then "finally" would be more appropriate.
At this point you have marriage, moving, etc., to consume your time. To that you
could add the stress of picking the right house in the right location, maintaining it, etc., but why...?
In your tax bracket, max-ing the TSP, HSA, whatever the phase-out allows for a tIRA and then the rest into a Roth IRA, makes a lot of sense. Per your OP (BTW, well written!) you would still have ~$10K/yr left over to put into taxable investments - even more if you rein in some of that (e.g., $2K/yr for clothes?!) spending.
Doing a case study on your combined finances also seems a good idea, regardless of whether you post it here or simply discuss it between the two of you.
And finally...good luck!