At 15 weeks, this is exceptionally normal behaviour.
Pups are playful and energetic and explore their world with their nose and mouths.
While the attacks may seem aggressive and the biting may hurt, it really is just play.
There are several things that will help
1) Keeping Heidi occupied with lots of mental and physical distractions. This means exercise, training, puppy safe chews, scenting games etc. The busier she is, the less energy she will have for 'annoying' puppy behaviour.
2) Positive reward based training. Work on a 'settle' command. When she lays on her mat and is still she gets praise and treats. Boisterous behaviour gets no reward.
3) Avoid any sort of punishment or shouting which will add to anxiety and can make the behaviour worse. Rather, ignore her sternly. This means you stand up, turn away and cross arms. It helps to wear long trousers and sleeves. Try not to make eye contact or to talk to her. Once she settles, she gets that attention she is craving
4) Time! She is at the most difficult and attention seeking age. Things will get better as she matures