Nausea & Cravings

I'm 7 weeks pregnant and have been having occasional on and off nausea (no vomiting yet) and dizziness. I'm still trying to exercise or go for long walks and drink lots of water. But I've been craving salty foods like crazy. I've always had such a sweet tooth and ate a lot of grilled chicken, salads and fruit. Most foods now, just the thought or smell makes me nauseous but I'm able to eat grilled cheese, soup, and yogurt, and really craving cheese, chips and pickles. Should I be worried that I'm not giving the baby proper nutrition and too much salt? Did anyone else have issues eating a balanced diet when nauseous? How long will it typically last?