Sounds like there's a few problems here.
When paint bubbles or blisters it could be one of a few things. For simplicity's sake we're going to assume that there is only 2 types of paint: Latex and Oil. Typically when you paint over one with the other without priming the wall first you will run into a problem of the paint not adhering to the wall (just like oil and water in a glass, they don't mix), this will cause the paint to separate from the wall, when there is a temperature change in the room (like from a shower) it can cause the air pockets to expand forming blisters. This can be solved by stripping the paint, sanding, priming (with your choice of oil or latex, but stick with one type), then paint (with the same type of primer you used). In bathrooms you typically use a higher gloss than elsewhere in the house as it has a higher resistance to moisture, they even make specialty paints just for bathrooms.
Bathroom being cold:
Your bathroom may not be insulated properly. Insulation will need to be placed around all walls including behind the shower wall, also your pipes should be insulated as well to prevent freezing. Also if your bathroom is at or below grade consider insulating the floor and ceiling as well, heat loss will occour anywhere there is a gap.
A fan that has an adequate CFM is a must. That moisture will linger and eventually impregnate any cracks, which will in turn damage your walls, tile, and everything else (which could also be a cause of paint bubbling). Ensure your fan is rated for the size of your bathroom, and when you shower leave that fan on for 20 minutes after you leave to ensure proper air movement.
It's tough to say what's really going as sometimes problems like this mean that you have damage inside the wall, so my suggestions may not work until you've solved whats happening underneath it all, for that you'd have to open up your wall. This may not be such a bad option as you can ensure proper insulation, proper water/moisture resistant gypsum board, and apply the proper paint, while you're at it install a new fan. Hope this helps!
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mikeasaurus' answer is excellent.
You can also use floor rugs to protect your feet from a cold floor. Don't leave them wet though, as that could exacerbate your paint problems. Hang them up to dry in circulating air if they get very wet. They will also act like insulation (not as good as actually insulating the entire floor though).