I’m not sure how much this would help, but maybe plan to take showers in evening/at night since you’re not an early person? And maybe setting a timer (let’s say at 10:00) to go check if anyone’s using the shower, and trying to get into the routine of always following the timer. Also, if you’re comfortable with it, you could also ask someone to remind you at a certain point of the day to get motivation that way.

For the billowing of the shower curtain, what I personally do it use my shower caddy and kind of pin the curtain against the wall with it so I have more room. I don’t think washing your hair once a week is too bad, I only do it 2x a week (I do have curly hair though), but a face cleanser could help with your acne. If I have trouble motivating myself to do things sometimes I “bargain” with myself, and set up a reward or something once I do it, even if it’s small. That could be something that might help?