Any advice is appreciated please

So I’m only 19 and I haven’t been sexually active for long but I’ve recently got back with my ex and we had sex on the 13th of March. I was meant to start 5 days ago so I took a test yesterday and it came up negative. I still haven’t started. I’ve got sore nipples which I never get and I’ve had some cramps usually they’re really painful but now it’s just like a dull ache or something like a poking pain which is strange.

Could I still be pregnant even tho I got a negative result. I don’t want to think the worst and now I’m extra confused because it came up negative I’m never this late and I’m panicking.

Thank you in advance :) x