I’m not very strict with any spread rules your whole practice is up to you. Just decide before you pull cards so you don’t change the meaning on yourself later.
If you’re seeing weird results, I would take a break for a day or two and come back with a fresh head.
have you tried shuffling between each card? when the energies feel blurred it might be because you’re pulling from one continuous moment instead of three separate ones. i usually draw a card, hold it for a sec, then shuffle again before the next one. helps create some separation between past, present, and future readings.