Make my nipple sucker suck harder?

I have a Medela automatic breast pump that I use purely for pleasure. I really enjoy it but I would like it to suck my nipples HARDER.

Any mechanically-inclined folks and/or physics geniuses have advice on what to adjust or how to modify it?

My set up: I use the nipple shields that are about 3” wide with stems about 2.5” long. I made holes in a sports bra to keep them in place. I don’t actually produce milk so I just put masking tape over the valves where the bottles would screw on. The air tubes are about 3 feet long.

I’m hoping my solution will be as easy as changing the size of one of those parts or taping something differently. 🤞

PS- pls don’t suggest buying a new one, that’s not an option rt now.