How can I keep my shower curtain from blowing inwards while I'm shower

Either attach heavy weights or magnets in the hem.

Turn down your water pressure . Get a new showerhead with energy efficient mark on it. Or hot glue magnets to the bottom of shower curtain. Good luck

In addition to adding magnets, which should already be there, you could try a different shower rod. Use one like hotels use that has bow (arc) outward from the tub, or try moving your existing rod further out so your shower curtain comes down at a slant \ instead of straight down. I purchased one of the curved shower rods and it helped tremendously with that problem. I don't see any difference than if I had moved my original rod further away a couple of inches.

Glue some magnets to the bottom. They will stick to the tub and the curtain will stay put.

I have the same problem. I added heavy weights about every 12" to the curtain. Didn't help. I'll try the arced rod or maybe moving the rod out a bit.