Food amount

I am feeding my 1700g ball python every 7 days 4 mice that weigh together circa 90g, is this enough or give it more ?.

thats not enough no, She wont continue to grow, but maintain at that, Have you tried to switch to rats? It'd be much cheaper and 1 feeding vs 5+

I do stop at medium for my 1600+g females, which are usually 140-190g (somewhere in there i never feed large/jumbo)

If it is a male, you are probably fine. If it is a female and she is just a pet, you are probably fine. If you want to use her for breeding, she'll need to eat more to be able to support the demands of making eggs.

I feed 6 weeks old rats which are about 120 grams to my biggest girls over 2000 grams, even to those who are close to 4000 grams.

Anything below 2000 grams I feed rats in the 80/100 gram range.

Males I feed less, 50/60 grams rats

Small rats are usually around 60/80 grams

Medium rats are 80/175 grams

Your feeding is fine, keep in mind that in captivity we are overfeeding anyway.

Now if the animal is a female you wish to breed you can increase feeding right before breeding season feeding every 5 days instead of 7.