I'm in a similar situation right now, and I've been in this kind of place many times before. I try to keep the seemingly idle time to a minimum, but I also acknowledge that my brain is still thinking about the problem during those times, so I don't beat myself up about it and go for a walk when that happens.

The self-doubt is also normal, and I actively push against it by reminding myself that, while someone that has done this before can likely jump to a good solution right away, it doesn't mean that it's realistic to expect that of myself.

Being tangled in a mess of something you are not an expert in is a normal way to learn. I have to remind myself that this approach worked before and there is no reason to believe that it won't work this time.

I'm going to put these tips to good use today:

I don't know if this is the right module to use for this. It looks like it doesn't do X and Y. Screw it, I'm going to try to get Z working.

I can't figure out the proper way to pass this argument in? Let's just hard-code it for now to get things working and mark it with a TODO.