I dont really have much addvice to give you and sounds like everyone has given you heaps of great stuff anyway, But here is what I have to say anyway...
My mum was told when she had my sister over 35 yrs ago that my sister was hyper and no to give her red food colouring ( ADD and ADHA werent around then) but she went to her doctor one day as she just couldnt cope and felt like a horible mum as she felt like she couldnt love my sister like she did the rest of her children and this is what the doctor told her and Mum has always said it was the best thing she had ever heard so now I will tell it to you... No one ever said you have to LIKE your children but you will always LOVE them and there is a big difference, between love and liking someone... So never feel you are bad a bad mum or that you are doing something wrong and I truly hope that you find the answers you need soon...
I hope this might help you when you are feeling low