I was in your position as well and my recommendation is to buy a good book.
I personally chose Precalculus by James Stewart and it works for me.
It's a thick 1000 pages book with excercises and tests.
It quite well explains all topics, which you would have in high school (from basic arithmetics to everything you need to start calculus).
I do maths in my spare time (a few hours a week) and I completed 700 pages over past 3 years.
This year I should complete the book and be ready to do more advanced mathematics.
95% is self explanatory (if you focus and re-read) and explains well proofs. When I didn't understand something I found answer on google or asked a few questions on math stack exchange.
My point. You can absolutely do maths on your own. You don't need classes with a teacher, but it only depends what kind person you are and what works for you.
EDIT: Do all exercices and never skip to the next bit if you don't understand something from the previous part.
You are very persistent! But the efficiency is too low, not to put you down but precalculus is not something you should spend so much time on, there are so much more to learn and so much more fun after precalc. At this rate, it's probably going to take you 10 years to complete calculus and differential equations, which typically college students take a year to finish and start applying. Plus there are abstract algebra, discrete mathematics, etc. I know you are probably having fun with the precalc topics, but trust me it's more fun afterwards. Imagine what you are learning now is from times before 17th Century, and you wanna catch up to all the fun today at that rate, it doesn't sound fun.
Firstly, maths is just my hobby. I didn't pay much attention in my school years, but later in life I wanted to know more about maths.
I'm a typical code monkey, which does business software and hardly needs any maths, so agian maths is just my interests and I don't foresee using it in my career. I might do more maths when I retire as maths is such a broad subject, it will keep me as a hobby to the rest of my life :).
I'm taking it slow as a) I'm not in hurry, b) I want to have solid foundations in maths. I want to ensure I understand well basics and proofs and where they come from. I also do lots of exercices based on acquired knowledge. "Productivity" is not my main concern :)
Interesting thing I found maths helps me with my work indirectly. In maths we encounter problems such as "a plane flew north at 300km/h and side wind east was 30km/h. After 2h, the plane changed direction 30deg...". You need to find all data and best formulas for the problem. It's like translating customer/project owner issues to technical ones. It's fun!
I wish to progress my maths faster, but I can do only x hours a week and want to do it properly. I'm looking forward to more challenging 21st century maths!
I personally chose Precalculus by James Stewart and it works for me. It's a thick 1000 pages book with excercises and tests.
It quite well explains all topics, which you would have in high school (from basic arithmetics to everything you need to start calculus).
I do maths in my spare time (a few hours a week) and I completed 700 pages over past 3 years.
This year I should complete the book and be ready to do more advanced mathematics.
95% is self explanatory (if you focus and re-read) and explains well proofs. When I didn't understand something I found answer on google or asked a few questions on math stack exchange.
My point. You can absolutely do maths on your own. You don't need classes with a teacher, but it only depends what kind person you are and what works for you.
EDIT: Do all exercices and never skip to the next bit if you don't understand something from the previous part.