Safety concerns aside, I'm impressed you were able to contort yourself like that.
I felt like a superhero when I nursed DS on a crowded subway train and didn't make him unlatch to exit the train. I finished nursing him on the subway platform. (He was about 1 month old at the time. I think he'd be too distracted now at 7 months for that to work).
I can't think of anywhere else I had to use real physical skill to nurse.
Please don't feel like a bad parent. We all do things we shouldn't whether because we feel like we don't have a choice or we just don't know any better! The important thing is to learn from our experiences!