Biting/fighting children

Sadly I'm pretty much at the end of my tether with my job how it is currently. I previously looked after mostly boys since they were babies they went off to school In the summer and my new July intake was made up of girls, so I currently care for three girls all aged 18-24 months and it's honestly the hardest job I've ever had in the 17 years I have been workin in childcare and I don't know what I should do now to make things better.
One little girl is so clingy and has strong seperation anxiety so she needs a lot of attention from me but the other two girls are the main issue they fight all day long. One of the children hits, pulls, pinches and pulls the hair of the other child and then the other child retaliated by biting then the child who started the pushing then cries about it. The other child is a biter she's 18 mths and it's always done in frustration I'm working with the parents by making sure we deal with it in the same way, but the other child is 23 months and is screaming at me saying "she wants to do it" when I tell her not to and it's constant between the two of them all day long.
I've tried ignoring bad behaviour, praising good behaviour, time out, speaking to them on their level depending on their stage of development and nothing is working.
I speak to the parents everyday who say both the children are also being naughty at home and they don't know what to do, both parents are very soft on discipline.
These children do full days, the same hours everyday and I'm completely exhausted and crying and can constantly moaning about it at the end of the working day and have started to really hate my job.
The children get a lot of attention from me in fact I think they maybe get too much as they need me 99% of the time, I provide lots of fun, stimulating activities and we go out and about but after one bit another child at a toddler group the other week I'm not going to them anymore as I'm too worried she will keep doing it.
Anyone been in a similar situation before and have any advice please!!

Oh poor you! It does get better and they will grow out of it if it's managed consistently but it's so hard when they are doing this :(

Lots of outings - go to the park, feed the ducks, run round the big field - getting out often defuses the situation.

And consistency - parents have to be supporting you 100% or it will take a lot longer.

You might feel you have to give notice to one of the children ... it's not a failure it's just some mixes don't work.

Hugs xx