Firstly, to realise that things aren't working well and ask for advice means you are already on the right track.
Obviously this is just an idea, because we don't know enough about your situation but from your post it sounds a little bit like you feel you are doing a lot for them, but their individual behaviour towards the family isn't great.
I would try to think if by any chance you feel you overcompensate due to splitting with their dad, and to try and show your girls what a great mum you are, and not how you are depicted by their father.
Are you proving something to them, to others ? I think if you feel too strongly about making sure have everything and every opportunity then sometimes it's difficult to stop giving those things. You feel like it's a punishment on them, rather than just normal life.
I believe that normal family interaction, simple things like respecting others in the family( not making others late for instance), compromising, helping out when needed or a part of weekly chores, is part of the "basic" package, but the one that requires most of parents time and energy because it's created by consistent parenting and being there to encourage such behaviour.
I know that I personally would have struggled to do that in a calm way and also enable multiple extra curricular activities that required ferrying around. I wasn't a single parent but spent lots of time parenting alone and I had to adjust my expectations while my children were small . I didn't have the mental energy to do it all so concentrated on the basics. Obviously there will be many parents who can manage more than me, and others who can organise more help.
I'm not saying you should necessarily stop doing things, and certainly not as a punishment, but I believe that if you are pushing yourself to the limit as a parent it's not easy to have the patience to deal with day to day things in the best way.