I never had much enthusiasm for math in school and, at the college level, I took zero math courses. I minored in astronomy, which did require some basic math and physics skills. But aside from dragging down my GPA and raising some eyebrows in interviews, it's been no help to me at all.
Interviewing for a first career-type job can be a demoralizing process. I studied German in college. German. That's not a very useful major in the US! But it's what I loved and was passionate about, and while my friends complained about their workload and course work, I breezed through and enjoyed school.
I think when the time came to apply for jobs, I was prepared for rejection. I felt like my choice of major meant I had an easy time in school, so it was only fair that I would have to struggle to find a job. I thought about all the times my friends would complain and panic about their grades. I used to feel guilty, like why did I have so much downtime? Why did I have such an easy life? So on the job hunt, I was just like, this is it. This is my turn to suffer and panic and be stressed out.
Anyway, I interviewed I ton. I got over my fear of interviewing by just doing it over and over, even for jobs where I was clearly a wildcard candidate with no real shot at getting an offer. I interviewed for management type jobs, I interviewed at a bank, multiple law firms, the corporate office of a grocery store chain, marketing, a cybersecurity consulting firm, and other stuff I can't even remember. I had close to 30 interviews, and applied for nearly 100 positions. At some point, it became kind of fun! I just threw myself into it, crafting cover letters and follow-up emails and networking with alumni. I devoted all my free time to it and turned it into a game.
Anyway, in retrospect, I feel like 90% of the jobs I interviewed were not a good fit. I would have accepted any of them because I was a desperate college student, so it's a good thing I got rejected! I ended up in technical writing and love it. I honestly can't imagine doing anything else and liking it half as much. But at the time, it was just another interview. I didn't have my heart set on it. I didn't think, "That is what I want to be doing next year."
You're being very hard on yourself. Focusing on your shortcomings is not a good approach. If you didn't put the time or effort into mastering a hard skill in school, you have to do it now. Now is your turn to show your mettle and grit. Maybe you have low self esteem because you didn't challenge yourself enough in school, but why not start challenging yourself now? Being a teacher is an obvious kind of occupation. You've spent most of your life interacting first-hand with teachers. But there are so many other jobs out there. It's just you have to dig, you have to hunt. It's easy to beat yourself up if you're standing still, staring at your own navel. Just throw yourself into the job hunt the way other people threw themselves into their schoolwork.
You're a good writer and have a lot to offer a prospective employer. But nobody is going to value your skills if you don't value them yourself. You set the tone for how other people see you. It's not up to the interviewer to tell you whether you're cut out to get a good job and have a good life. I think you're giving too much power to other people, instead of recognizing that the common denominator is you. So chin up, good luck. PM me if you need someone to proofread your cover letters.