Mine is the same, he can use the fork but not the spoon, and can drink from a glass but can’t manage to use the straw.
It’ll take time to learn to use them if he hasn’t been given opportunities to try at earlier age. I have let my children use utensils whenever I think we can afford to be a little messy, and that has always been the way we eat since we started solids. If you only just started recently the. You just need to be patient. It will eventually happen.
Don’t put too much pressure on yourself or him. Give him the cutlery with means and encourage him to use them. Maybe try mummy do one you do one. Try play activities that use similar movements. If still concerned speak to your health visitor.