MS in Mathematics, having trouble finding work outside teaching algebra
First of all, jobhunting s u c k s. It sucks even more when you're trying to get into a field and it sucks further if you're not in a major metro area. It's a massive timesink with terrible ROI, but it needs to be done in order to get a job at all. The truth is that whether you get hired isn't going to just depend on your skills and experience, but also on whether the person reading your résumé thinks your skills and experience line up with what they think they want, and you don't have a lot of control over that. So honestly it's impossible to predict how long it will take before you find something.

That being said, your situation really doesn't sound so horrible to me. You're interested in and studying things that (1) you want to do and (2) employers are looking for. You have a master's degree in a marketable field. As for whether you feel you learned much during your degree, it sounds to me like you're just in a bad place with a killer case of impostor syndrome. Some employers might want to see your transcript, but they're a lot more interested in what you can do for them. So maybe try putting together a portfolio of the kind of work you want to do, which might include models or software that you developed or small projects that you did for free or for cheap for someone. (These are pretty standard suggestions.)

Finally, you can't be everything to everyone. It might feel like you need to cast as wide a net as possible, but it sounds to me like you might be spreading yourself thin and that's contributing to your frustration. Narrow it down some by considering where your best bets are in your geographic area and what you really want to do. For example, if coding is the right path, then back-burner the modeling, or vice versa. Good luck.