8dpo symptoms

I’m having constant dull cramps on my left since 6dpo but all of the test I’ve taken are negative if the implantation calculator from online are correct I could be having implantation symptoms today or tomorrow since it’s when it would be most common for implantation. Apart from camps I have back ache and achy left hip, mild heartburn, increased appetite, frequent urination, sore nipples, and pinching - gurgling in uterus, what could this be?! I know it’s too early to test and I could get a bfp at 12dpo but I feel pregnant one minute and not the next - have anyone of you guys had these symptoms and turned into a bfp

P.S I had all these symptoms with my first