iPhone back up storage

Hi

I need help with my iCloud storage. Since I had my new phone my iCloud storage is almost full. With my old phone I had used less than half the 50g I have in the iCloud & now it’s at 47g. It says the back up takes up half of the storage and I don’t know why. Also my photos are taking up more than double the amount of storage they used to on my old phone. This can not be right!!

I hope someone can help as I do not want to have to go to 200g or storage for £2.49 a month.