Yes, 7 weeks is very young to be away from her mum. Kittens mature a lot between 7 & 12 weeks and are much more able to cope with the stresses of a new home when older.
However you have her now, a vet visit is in order. He will also give her a general check, and she should be wormed and checked for fleas as well. You can discuss vaccinations and neutering while you are there.