Sarah is Stubborn?

Libby has been stubborn since birth. When a child won't eat for no apparent reason except that they don't want to (and might have reflux, okay) but seriously, we knew she was stubborn right away. It is turning out that Sarah is stubborn too. We attempted potty training again this week. She clearly has the bladder control. Day 1. Dry through a 3 hour nap, only one accident, even pooped on the potty. Day 2. Dry in the morning and went once in the morning. Then as the day progressed, she got increasingy upset about the idea of sitting on the potty. This escalated as the days went on. The last night she held it for something like 6 or 7 hours before Derek finally placed her on the potty (letting her hit him and scream) and she finally went. She is SO MELLOW about most things. Somehow, she has been turned off from going potty. She likes the independence of diapers? She likes it when we aren't following her around and reminding her to let us know? She must definitely prefer it when we don't make her try occasionally because it has been far too long? We gave up, again. I guess she knew we would. She had her insides in such a snit that she gave herself the runs, and diaper rash.
I am going to just appreciate that Sarah is mellow about most things, but I can't help being puzzled about what her hold up is with going potty. We won't try again until she begs. Even if we have to drain our savings to pay for diaper rash meds and diapers.