If you were a juvenile, that would change the dynamic of the proceedings.
If the attorney told you that you could get 30 days in jail, then it is very likely that he is right. He would know more about the situation than we would so he should have a much better feel for what could realistically happen.
Until you go to court, you may not know if the DA even intends to pursue the matter. It could be that the DA will feel that a tale of conflicting statements is not worth pursuing ... or, they might believe dad over you. We cannot possibly know.
Keep in mind that if this is dad's home, you might want to find a new place to live because dad could evict you. And, if the two of you are not getting along, it's probably a good time to move out.