I know a person who tried Khan Academy to get caught up on math after a pretty poor childhood education (they didn't finish middle school). Their feedback was that they were able to get their fundamentals down enough to actually pursue more advanced topics fairly easily (about a year of self-study to go from zero to 'high-school graduate' level.)
From my own personal experience, I would recommend getting to the high-school graduate level and then taking some classes at your local university or community college for topics beyond trigonometry. You'll likely be able to handle everything up to that point on your own without much support, but many people struggle at that point and benefit from having people to ask for help when they need it.
I would wish you the best of luck, but I have no doubt you'll get to where you want to be without it.
From my own personal experience, I would recommend getting to the high-school graduate level and then taking some classes at your local university or community college for topics beyond trigonometry. You'll likely be able to handle everything up to that point on your own without much support, but many people struggle at that point and benefit from having people to ask for help when they need it.
I would wish you the best of luck, but I have no doubt you'll get to where you want to be without it.