I find my pump stops or sounds deeper when the pressure is getting too much. The hand vacuum pump has a pressure gauge on it which was really useful but the battery pumps don't, might ask OH if we can put one on?
I'm finding Willow, also a first time milker giving more each day as she gets used to it all, took me weeks to even persuade her to get in the milking stand but now the kids are off her at night she's glad to offload some I think