Could I be pregnant

We've been trying for a couple months for a baby following coming off the depo back in August. My period returned after 3 months and are regular around 28 days. Last month I was almost 2 weeks late. 2 negative test later I booked a doctors appointment but the day before the appointment I had my period. Standard 5 days medium flow. But I've still got really sore, heavy boobs, they've got bigger. I feel nauseous in the mornings. This is now 3 weeks since my period. Could I still be pregnant?