I don't use ProZinc, so I don't have any practical experience with it, but I'll tell you what I see
You skipped last night, so that's going to effect the numbers some. Now ProZinc isn't dosed like Lantus, but the usual protocol I've seen used here either uses the same dose at AM and PM or there's a sliding scale used that says if they're at X number, they get Y amount of insulin
ProZinc does need to be given every 12 hours though, so we need to figure out either a dose that can be given every 12 hours that doesn't drop her below 50 or decide on a sliding scale for her that you can use
Can I ask where you came up with your dosing schedule? Usually, if a sliding scale is used, it's more like if they're 400+ they get A units, 300+ gets B, 200+ gets C and under 200 gets D
Stalling, while an important part of this dance does have one big problem that it looks like you ran into last night...while it's important that you not feed to see if the number comes up on it's own, if you stall TOO long, by not feeding the number keeps dropping until it's too low to shoot at all.