Hugs! I was on the pump 8x per day routine for the first 8 weeks of my dd's life, and I FEEL YOUR PAIN! I felt like I was being tortured and kept in a barn like a heifer. I can't imagine having to do it with a toddler.
I don't know how you help develop a baby's suck (our issues were different), but I guess theres a supply issue too? I got a prescription for one week of Reglan from my baby's pediatrician, it about doubled my supply in 3 days. I have heard domperidone is better and safer.
What about increasing nursing frequency in lieu of some pumping sessions? There are some slings you can wear the baby in and nurse, some people can even walk around like that (I never got the hang of it, but I didnt' have to chase a toddler then, I might have tried harder to master it)
Hugs! Don't worry about venting frustration, everyone here understands. You'll get lots of good info and support, and always NO JUDGEMENT, that's one of the best things here.