Welcome. Love your sign in name. My DH sometimes recites a little poem about "me mudder who made me pee when I could not" and it seems very appropriate for someone potty training a puppy. http://www.mamarocks.com/me_mudder.htm
How are you pronouncing Isla? As in island?
Yes, the growling is normal. If she is half Lab be prepared for a mouthy pup, after all, Labs were bred to use their mouths in retrieving.
Guess who has a Lab?
Be extra prepared because she left the litter far too soon. The weeks between 6 and 8 are when bite inhibition is learned from the siblings and your wee girl has been deprived of that.
Try to direct her to a toy BEFORE she gets a hold on your pants. Much more effective and at this point she has no idea what STOP IT means. From the way you worded this she probably thinks it means what she is doing because it sounds like you are saying it while she is doing it. That's how you are going to teach her potty words, by saying them as she performs, and the same applies to other actions.
A rule of thumb for puppy exercise is 5 minutes per month of age of forced exercise on a hard surface allowed twice a day. Forced is anything on leash, straight line and/or compelled to keep up with you. Forced is thought to stress young joints. Play off leash is unlimited because then puppy can change speed and direction and quit when she feels like it.
Plus you want to be careful where you take her before vaccinations are complete. Ask your Vet about this. Parvo is the biggest concern, though not the only one.
I bet she is one little cutie-pie. I know we all want to see pictures.
Take lots, they grow so quickly.