I need some insight..

Let’s make this short and simple. I’m 15 days late for my period, I had back pain for the first week after my period was late, occasionally very low key and dull “cramps” these days, not sleeping that well aka tossing and turning, cranky and always sleepy during the day...I was nauseous for a little bit in the first week of the missed period but haven’t had any problems since...I’ve taken a test every 3 or so days, each one comes up negative..I made an appointment with my OBGYN but the earliest appointment is August 27th...I don’t know what is going on..I haven’t been “late” in over 6 months, hell I’ve been regular as hell lately...My partner and I have had sex pretty often so I need to know asap 😅