Different ways of masterbating?

You are using the main ways, water, vibration and rubbing. Do not worry about pillow humping, it is just another way of rubbing. If you want more variability, use different positions. Kneel, doggy, sitting, squatting, laying, standing and so forth. Another thing you can do is to get yourself aroused to just before having an orgasm. Stop for a few seconds and start again. Keep yourself at the highly aroused state for a few minutes before allowing yourself to orgasm.

Please make sure you wash the massager before and after. There is a chance your mom is also using it for the same purpose like many other women do.

Take care!