I have been uncertain about my Ghusl and consider repeating my Ghusl and keep questioning my fasts. What is the best course of action for me in this situation?
Bismihi ta'āla
You must completely ignore and dismiss these thoughts of doubt. The best course of action to rid yourself of waswasah, or developing waswasah is to dismiss these thoughts and ignore them, and never repeat what you have done.
And Allah knows best