Keep at it
Dipole,
I know exactly how you feel. I remember feeling the same at your stage. it feels like you have a mountain to climb and no way in the world of remembring all that stuff.
But as you go through it bits from different subjects start to interconnect and it gradually starts to make sense.
To remember stuff you absolutely MUST make written notes as you go along. There's something about the physical act of writing that helps to commit things to memory.
it's also very important to go back over topics you've already covered. Make sure to build some time into your programme to do this. Don't expect to remember, for example, all your Air Law if you finish that subject and then devote all your time to the next.
Finally make sure your work programme is realistic. If you set yourself huge unrealistic targets for the amount of time you plan to work each day you will only become disheartened.
If you're working full time then plan on maybe just 2hrs a night during week days and perhaps 5-6 hours a day for the weekends.
Good luck and keep at it!