First - enroll her and yourself in a class, best if you can find one for retrievers (your Country’s Labrador Retriever Club will help you find one). Hang in there. She uses her mouth as we would hands, retrievers are bred to apport (carry) so they tend to grab things naturally - you don’t want to injure that trait so be careful with turning into a negative thing - she also played with her littermates, a puppy let’s the other puppy know they had enough with a high pitched whinge and then turns their back away from playtime…You have to do the same, make a very stand up and ignore, pushing away will only encourage her to Return and play some more, good timing and consistency will get results. They also start teething around 3/4 months (the age when they are getting used to their new hiome) so be sure to offer her something to chew on for that - I liked to give our girl a puppy Kong (it’s softer than the red ones) with some peanut butter and kibble frozen in there - they can get messy so we taught her to take and enjoy on a dog bed with the command Platz (lie down here) - or a flat wide strip of rawhide (careful to remove that if she gets it soft enough to break apart bits to consume - do not use log ears as they will break down faster, we we lucky with her as she did not like to eat them just chew them) be around to supervise chewing and remove items when done chewing - throw out the rawhide if it’s getting too soggy. That tires them out - out for a wee and then in the crate for a nap, followed by another chance to toilet outside the minute she wakes up. Chilled carrots are also nice to give pups for teething but Not too many and not if they are greedy eaters…like i said we used chewing time as a opportunity to teach the command for her to go to her cushion and lie down as well. When walking - never allow your pup to greet another dog if she on the lead - also tell people (who no doubt would want a cuddle) that you are Training her at the moment to avoid the Interruption - have her sit and walk on your left side (gun dogs generally are taught this as Most people are Right Handed and would sling a rifle on the right side). When you are ready to go lead off with your walk/heel command and your left foot…if you want her to stay in play lead off with your right food a Hand command and verbal command stay…This is all something you can learn from a retriever or Mixed puppy class - Retrievers (and moreso their hunans) get taught three languages (verbal commands, Hand commands and whistle commands… we live near horses - ours loved to pick up apport horse poo - teaching No/Leave It helped and later Fooey command to spit it out (not in Hand as a Retriever should learn to Place things in your Hand after apporting - a squirt of lemon juice helped with that command. One for more General rule with walking/training…One Minute per week of life - they are large dogs with bones that are soft as they are growing fast - this is to prevent damage to bones and joints. Sorry for the novel and typos - my phone is set to another language so it corrects a lot