If this was my space, I would start by patching the walls properly, and then painting the walls with a mold inhibiting semigloss or high gloss paint.

Next, I would remove the carpet and carpet strips. I might have to manage mold under the carpet. I have done this when my hot water heater leaked. I poured full strength bleach on the affected areas and let it dry for 24 hours with a fan blowing on it. Then I did it again, and waited another 24 hours.

Do you have the sliding glass shower doors on the edge of the tub? I would be very tempted to remove them and use a pretty shower curtain instead to reduce the amount of humidity in the tub area.

I would hire someone to come out and replace the backer board around the shower/tub surround, and the area near the toilet that has tile. Then you could choose to install tile again, or go with a fiberglass surround for the tub. You could install shower grade backer board where the tile is located near the toilet.,it is water resistant/water proof.

I would hire someone to install a good quality exhaust fan that vents to the outdoors. I would look into installing a skylight to solar tube for more light in the room.

I would get the counters as clean as possible and save up enough money to do those next.