I simplify it to two things:
1. Goal
2. Process.
First, you pick goals that makes you happy. I think the big fallacy people make is assuming that marriage+kids makes me unhappy vs being single. You can be perfectly happy doing either. You can be completely unhappy with both paths too.
It's also extremely difficult to decide which one would make you happier. Sure, there are frameworks for each. But the variance is huge. And 'happiness' isn't a fixed number. It's a Δ. Whether you're at 500 happiness or 5, you feel the same.
You can be married to a dream girl, have a dream job, have a million dollars in the bank. Then suddenly someone steals half a million from your bank account. You would still be unhappier than the 45 year old homeless man who got offered a grocery manager job.
So, I look for the Δhappiness.
It's also important not to turn back on decisions. I'm married and have two kids. I cannot choose to have one kid. Even if I had financial troubles or found a better girl, divorce or infidelity would make me very unhappy. There's no way I would put a goal in mind to reduce the number of kids or find a woman good enough to have an affair with. There's no way I can regret past decisions and be happy too.
One of the downsides of overcalculating is that you'd tend to assign values to things and inevitably regret something.
So I pick a goal, any goal that makes me happy and is achievable, and then burn the other options.
Next is process.
I look for the best process to hit that goal. And just stick to it. I chose a path as a startup developer. I optimize to be the best startup developer I can be, and ignore the things that would land me a job as a manager, CEO, or a FAANG developer.
Now abandon the goal completely. I may reassess my situation periodically, but I don't stay too obsessed on being a developer. If Google offers me an interview, why not?
Goals are difficult to hit because of all the factors in the way. It's easier to just focus on the progress. It's what athletes do win trophies and break records. Nobody can set a promise to win a match 3-0; they can only improve the process to overshoot that goal. Hitting a goal can cause complacency, missing a goal can discourage. Let the process do its work.
If you commit on focusing on your career and not having kids, then design a process to make you the best career man you can be. If you choose to do both kids and career, design a process to be a great dad while being great at your job with your limited hours. If there's no chemistry between you and your partner, create some.
Remember to ditch all the math that got you to your current situation. When assessing the future, you have to recalculate everything.