Maybe it is time to see a developmental pediatrician?You say she is behind, though I reallyhate even teh concept that a child can be behind in preschool, or that they are "teaching" to preschool.
Maybe a montessori preschoolll (a good one) would be helpful. My kids were in one for a number of years. With Jess they finally came to me when she was 2 1/2 and ASKED for us to get panties for her - she hadn't gone in the pullup for weeks. My oldest potty trained at 3 1/2 so I wasn't even LOOKING for potty training yet, LOL! (Blind mommy moment).
I really do nt know if this is defiance. I would push for some testing, because there are too many red flags with this.
Depression is a mental problem. Period. doesn't matter how you treat it. Alcoholism is usually a red flag for mental illness. Many alcoholics are self-medicating other problems.
It may even be that being around an alcoholic is causing problems for her. She has to know something is not normal, kids always know, even when we think they don't.
Personally, as the toileting issues came back suddenly after not being a problem, I would see a pediatric neurologist. You have seen the gastro, and don't think it is a problem with her urinary system.
I am really wondering about the possibility of seizures. A sleep deprived EEG done by a GOOD pediatric neuro is really important. It used to be that anyone with an ADHD diagnosis got one of these tests to rule out seizures. With my kids, we went for the test when ADHD was suspected.
Guess what?? My daughter, who NO ONE expected to show any problems on the test, has epilepsy. the siezures are almost unnoticeable, but they are there.
Seizures will cause all kinds of behaviors that you wouldn't think were seizures. Heck, they are even starting to think migraine headaches are a type of seizure in blood vessels.
I know how hard this type of problem is. Stick around, and please know that any suggestions/advice are meant to have you take what will help and leave the rest.
Hugs,
Susie