Who goes to fittings?

It is common for the bride to go alone until the last fitting at which time she brings someone to learn how to do the bustle. Usually there is not a lot of room where you get your alterations so your bridesmaids may not have anywhere to sit and/or stand.

I only plan on bringing my mom.

My mom, grandmother, and FMIL went with me to the first fitting! I don't think it's rude to limit the number of people who come with you, though.

For mine, I opened all of the appointments up (dress shopping, first fitting, final fitting) to whoever of my bridesmaids was available and my mom & step mom. Each one had mom & step mom, and then one or two of the bridesmaids. Basically whoever was in town and had the time available. Otherwise, they joined by Facetime or just saw some pictures after.

The final fitting I had my mom, my step mom and one of my bridesmaids who was kind of the "go to on wedding stuff" since she was the only one of us who had "been there, done that" with the big wedding a few years back. So she knew what questions to ask, to make sure to sit down, knew how to work the bustle, etc. It's nice to have everyone there for the oohs and ahhs, but realistically, keeping it small for the fittings is best.