When I left school, I found myself in a similar boat, and decided to set a goal of getting myself the knowledge equivalent of an undergrad degree in math. I alr

When I left school, I found myself in a similar boat, and decided to set a goal of getting myself the knowledge equivalent of an undergrad degree in math. I already had a physics degree under my belt, so it wasn't as long of a path as it might be for others, but over a bunch of years of self study it paid off. When it comes to your career a few years is nothing. The strong foundation pays regular dividends because learning things that use it comes so much more quickly. It's a huge, slow, painful investment, but totally doable and with tremendous ROI if you want to work with stats/ML/optimmization/really any numerical computing for a living. The reason I recommend this route is that most of the more advanced math books you will encounter will assume this stuff as the readers' common knowledge. Having that foundation, the majority of the literature is already tailored to you!