I guess it depends on why the other guests weren't invited. Did they tell you they weren't coming? DId you only invite family?
You are only supposed to invite wedding guests to a shower, but it sounds like your mom wants you to have some kind of big party! I would feel a little awkward if I were invited to a shower, but not a wedding. I would say if friends who aren't going volunteer a small, intimate shower is fine but a big one might be taken the wrong way.
Have you thought about making it a co-ed shower, with all of your wedding guests?