Is it legal to be arrested for DUI at home with a .06 BAC?

My husband and I went on errands from 1 pm- 5pm. We came home and poured a 3 ounce glass of Bailey’s and took a sip and realized I needed to drive down the street to get shelf lining to finish my job before kitchen contractors come the next morning. My son was home for Sunday dinner so I also picked you a few things I needed as well. I was gone about an hour. Tired from all the running around and 5 hours of sleep before, I wanted to relax and then start dinner, so I drank 2/3 of the 3 ounce of the Bailey. Then about 15 minutes later, there were police out front. He smelled the strong Bailey’s on my breath and proceeded to interrogate me. Three police cars where there. The officer said that someone smelled alcohol on my breath and that I was driving erratic. I was not more than 5 minutes from my home, pulled in and ask my husband upstairs on the computer to bring in the groceries, etc. He didn’t, as usual so I went out front barefoot to get them and was approach. I was not intoxicated at the time but tired. I failed the Sobriety tests- sloped street, little pebbles, dark and scared to death. They told my husband to bring the groceries inside the house- he did. But I was afraid and asked he be there for support, he said no. They took my license from my purse inside and arrested me. We went to the police substation and he gave me to Alcohol Breath test while handcuffed in the back seat. Both were .06 BAC. He said then I must be on drugs and the blood test would be inconclusive. I told him several times in front of the house and at the police station that I do not do drugs of any kind, only Tylenol PM sometimes to help me sleep. I was taken several hours later to OC Jail, booked and spent the night (9 hours) in that god forsaken place. I have only been pulled over once in my life 17 years ago for going 5 miles over the speed limit on my way work. Court date is in two weeks and the DMV hearing a week after that. I am 60 yrs old and the one moving violation (in 44 yrs driving).