Hi C.,
It is interesting that your son potty at day care but not with you.
When my first son was two, he had potty training down pat, but then little brother came around and he decided to wet all over again.
I would leave him in his undies, not papmers or pullups and when he got wet I would ask him to get another pair of shorts and undies and I would stay in bed with the baby while I gave him instructions.
Then- and this was key cause it worked for me- I told him when he had to go again, he had to tell me before he wet and I would stop whatever I was doing and would sit in the restroom with him.
The next time he had to go he told me, I made sure the baby was safe, he was crying, but he was safe. I went to the rest room and spend the whole time with the older son. It took no more than five-ten minutes and my younger boy was safely in his bassinet.
A few days like that and he was on his own again.
The key was he wanted my undivided attention.
As a recent graduate, I know how hard it is to give our boys enough attention when we are trying to please professors and get decent grades.
It worked for me, good luck.