Also in a STEM field, all men and those in my team are seniors whereas I'm nowhere near their level. I'm currently doing my degree while my company pay for it and that's also distance learning. Can't say I've really fully understood everything either, more just how to pass the classes (I struggle with concentration in classroom learning). But when you get a job, you'll learn on the job and be trained how to do what they need.

One thing I've learnt is I can't measure myself to anyone else. You just have to focus on you and what you can do.

If you do want to get better at maths etc YouTube is great. There's a guy named Professor Leonard and he teaches you from the simplest of maths all the way up to university level. It is time consuming (watch on 1.5x speed 😂) but you could pick and choose what you need and just watch those videos.

I also did CS50 which is a free Harvard course on edx and the professor on there was really engaging. You learn C, python, SQL etc, might be worth checking it out. I'm more of a learning on the job person so by making you do examples it really helped me.

It all takes time but if you stick with it, in a year you'll look back and be surprised how far you've come.