[bryanph_]

There is no such thing as "bottoms up" in mathematics, I think a relatively broad examination of mathematics might be useful so that you can discover what is relevant to the subjects you are actually interested in. I learned this the hard way. Here you have Feynman talking on this: https://www.youtube.com/watch?v=YaUlqXRPMmY Finding a real world use case for the math you learn will be crucial if you self-study to keep yourself motivated to keep going.