J.S.
I don't know anything about adhd, but it just sounds like your daughter needs to decompress after school. Maybe all she needs is a snack and activiity (like riding her bike outside).
We've all been waiting for winter to end - I think as it gets warmer and she can play outside, her behavior will change. I would keep on with the time outs for tantrums. This is what I tell my kids, "Go scream in your room. You can come out when you've calmed down." Same thing when they are disrespectful, "Go to your room. You can come out when you can talk to me properly."
My 8 year old (just turned in March) has been very challenging this year. It took awhile for me to get to the bottom of her acting out (talk about disrespect - Oy!). The "popular" girls at school kicked her out of their group. Who knows why. My daughter didn't know what to do about it, but was obviously upset. I gave her space to talk about it and made some suggestions, but mainly listened. I also talked to her teacher and the teacher reminded all the students about being nice to each other. Things have settled down at school and guess what? They are calmer at home.
Good luck!