Sounds frustrating. Have you talked with your attorney? Maybe he/she can recommend a better installer. Or at least help you argue your case.
For the rolling re-test when it’s going badly, how about pulling over. Stopping the car, relaxing (get out and walk around.) Then try blowing; maybe then easier to get enough breath to get to the sucking part.
It costs upfront to get a webcam for the car, but that may help in the future with supporting your contentions. At the least it’d show you were the one blowing. So a 0, high, 0 would have to be an error. The DMV is probably now assuming someone else blew the 0’s.
On the humilitation, that too take a breath. If a friend of mine got a DUI, and had to deal with one of these, I wouldn’t think humiliation. I’d think, worried about their drinking, if it’s a problem. And if a one time mistake, I’d think that.
There are a couple people here with a lot of experience and good ideas. You’ll get more used to it, and better able to manage it too, so it doesn’t error. Apparently taking the handset inside to work and home at night, helps reduce equipment problems. Bliddy and Wanttosucceed, and a couple interlock installers are around.
How long were you drinking and driving before it caught up to you? This sounds like a wakeup call. It’s frustrating, but it will be managable eventually, and you’d get past this. Have you asked anyone about carpooling, or paying a co-worker to pick you up, (it’s less than a taxi, more than a bus)?