Hi Ruby
I guess you mean 90f not c? so going on that would be 29c which you could go a little higher 28c-32c.
Sounds like you have a good set-up going there, is she active when you have had her outside?
Try putting the cuttlefish in the garden and get it bit weathered as they don't like fresh clean cuttle. Regarding the food I would not feed too much clover as it is high in protein for the hatchlings ok for the adults though, and nasturtiums are high in oxulates which inhibites calcium intake. Try giving her some lime flour which is easier on the gut, although she does need her sprinkle of nutrobal daily, so try putting the nutrobal on the food then rubbing cucumber over the food to disguise the smell, it is a case of the strongest mind wins!!
It isn't the right time to hibernate now, so I would leave that until next year, which will give you time to get familiar with what to do. Do you give her warm baths, that could get her going, and they love routine, for example I bath mine in the morning, we have a bit of bonding time and then food time, this works for us. With the weight issue, are you weighing before or after the wee's or poo's or food time as when they are little all these factors play a big part. If you are not happy then best take her to a vet for your own piece of mind, it never hurts to get confirmation that all is OK
I hope this helps, please ask if you are unsure about anything that I have said
Keep us posted
Jane