Exclusive pumping help

It's been almost 3 weeks since I had my baby and we just couldn't get a good latch. But I've stuck with pumping and I have a few questions:

Bras. I cut slits in an old sports bra and it's starting to split too much and won't hold the bottle up as well. I need some good bra recommendations!

Handheld pump. I know I'll be needing one soon. Recommendations?

Milk production. I've been getting an average of 3oz per boob from a 20min pump sesh. That's from pumping about every 3 hours. Ive been stuck there, any ways to increase my supply in the near future?

Also, between the pumping and baby changing and feeding and washing the pump parts at night...I'm hardly getting any sleep. Would only pumping once through the night hurt my supply? (Assuming my boobs don't explode).

All advice appreciated 👍