Thanks everyone for your replies! I did my best to follow KarenG's advice and keep a smile on my face. It was a little hard for me to do at 5 AM, without any coffee. In Milwaukee I politely asked the TSA agent for a pat down because of the pump. I waited a few minutes, because the non-stop flight was full, and then had the pat-down. The agent was very polite, appeared to be familiar with the pump, and it took all of two minutes. Returning from Boston, allowed plenty of time at Logan, after getting a ticket voucher was directed to the pre-check line and walked right through without taking off my jacket, shoes or answering any questions.
Although I'm not planning any additional flights in the near future, I'm now confident that I'll survive the TSA check-in. Thanks!