Is he ever gonna grow?

I adopted this adoooorable runt of the litter, my little boy "Ori" He's now almost 5 months old but he's still the size of a small kitten around 9 or 10 weeks. The vet says he's completely fine aside that he's recovering from worms and feline rhinitis. Sometimes I think he's a bit slow in general but he's trying his best haha! So my question is: Do you think he'll ever get bigger? He's only gained like 20 gramms in 3 months and he's only around 1 kilogram Also his new teeth coming in are super tiny as well.