I had the same issue two years ago after buying an iPad, and went through multiple tutorials (DrawABox, Udemy), some books. I wasn’t able to stick to any of them, until I stumbled upon some videos on YouTube by Alphonso Dunn. For some reason his way of teaching worked for me, so I bought his book [1] and I’m finally seeing progress.
If I may ask, how does one get "thrown into writing a simulation model for an attitude determination and control system with no prior exposure to orbital mechanics"? I always wanted to write software that deals in some way with spacecraft, but always thought one needs to have some physics degree for that.
[1] https://www.alphonsodunn.com/book