You're definitely going to need to know your fractions and decimals if you're going to do engineering. Also percents, units, etc. I would start with a good pre-algebra book. Then work your way through algebra I, geometry, algebra II, pre-calculus (including trigonometry, algebra III, and analytical geometry), calculus I, II, III, and finally differential equations. Depending on your motivation, that will probably take anywhere from 1 to 4 years. I would make sure that whatever courses you take, whatever books you read, are all heavily applications-oriented. For example: a good pre-calculus book is Morris Kline's Mathematics for the Nonmathematician. A good calculus book is by the same author. Those are very applications-oriented. As for differential equations, you almost can't go wrong, because the subject is so inherently applied (at least, in my opinion).
Anyway, that's the standard math track, picking up approximately where you are.