Our family have ALWAYS neutered all our cats and dogs, boys and girls, and never had a single problem

Cats are always done around 5 months before they start coming into season but I do prefer my bitches to have had a season and the boys to be a year old before getting them done.
ALL have retained their loving sloppy affectionate natures and lived to ripe old ages well into their teens

My first yorkie Scamp and our crossbreed Lady both lived to be 17 years old and our two Jack Russells Buster & Heidi were 7.5 (he was diabetic) and 15 respectively

The cats have varied from 13 up to 19 years of age
Have a chat with your vet and TELL him about your worries....he won't think you're being silly or over-protective, just a caring owner who wants the best for their dog