Bathroom Wall Texture Issue
Matching existing texture is an art. It is very hard to make it look like there was nothing done. Most of the time you hope for the end result to be that it is not noticable to others even if you know it is there. There are various ways to get a better looking job, it depends on how much time and effort you wish to put in. One, like you said, you can sand down the existing texture and retexture. Two, skim the surfaces making it smooth or then retexturing. Third, texture the patches, then retexture the whole room again, so a new texture sits on top of all the surfaces in the room to get it to blend. And fourth, just spot texture those areas in question to try and blend to the existing texture, which is the simpliest and easiest. If you haven't any experience, then you will find it hard to do any of them! But if you are young and want to learn, and might use the experience in the future, then it is worth the effort. For small patches, they have texture in a can. Practice will help before you attempt the final touches. For larger jobs, texture machine can be rented.