I did many things that may have been a waste of time, but I don't regret them at all. Or you can say I did many things that may have been a waste of time, but no regrets. There are a few ways to say it but I didn't want to move too far from your original words. If you want, I can write them in a comment afterwards.

I did many things that might have been a waste of time ,but I have never regretted doing them at all. I did many things that might have been a waste of time ,but I have no regrets at all. We use "might have " for the past . > DID is past tense I do things that may be a waste of time , but I have no regrets at all. I dont regret doing the many things I did that might have been a waste of time at all.

i have been waiting for her since morning for next movies whatever :) .... WELL here you use that is perfect but if you really talk about long time ago then you must use I've done......and them as she said.

Sorry ,it's "used as an transitive verb"

Thank you,I thought I used intansitive verb of "regret"which meant I didn't feel regret.But maybe it'd sound more natural to put "them" after "regret",used as an intransitive verb here ?