If she seems comfortable it is possible there are no more, but I would usually have a queen to the vet for a post-partum inspection just in case. If there are more, she may simply be taking a break in between labour. If she is still straining then the odds are in favour of more kittens. Also remember that a queen can have multiple simultaneous litters so may have a break between delivering them. It is far too complex to sort out by internet, better to have the vet to check.