Facing a 3rd OWI, not from alcohol, and I was offered plea to 2nd offense. I had hoped for a better offer

I am facing a 3rd OWI, no alcohol. My meds, same meds and dr for years, stopped over (speed?) on the way to work. I have Q’s with regard to the sobriety test the officer asked me to do. He stated I was under arrest because I forgot the directions of some of the tests and other than counting 1 one thousand and so forth and I touched my nose and didn’t immediately put it back down to my side. I don’t think there was anything else, and I thought these tests were all about balance and walking a straight line and not wobbling around with my eyes closed since I can’t step on my feet the same way anymore. I wasn’t going to pass balancing on one foot, and I said a couple of times I can’t do this or walking the straight line which I did better than I expected. I asked to just do the breathalyzer, I figured he thinks I was drinking, and I just wanted my tickets so I could go to work. I really thought my balance on my feet would prevent me from satisfying the test, and I was going to be asked for a breathalyzer. At the jail, the officer said I had a really bad luck night because another officer would have let me go, but he’s trying to become an expert in this type of thing, so were the tests about me or was he biased?