Implantation Bleeding or Period?

I got off BC in Sept 2018 so husband and I can TTC. Periods have been every 28-30 days each month with extremely heavy, bright red flows for 3 days & severe sharp pains with first day on period. No other symptoms.

Last week:

- light to moderate brown discharge 3 days before AF that continued for 2 days

- mild cramp once on day 1 of discharge with serious headaches and fatigue (I never experience either, I’m extremely active with weight lifting and take a lot of supplements)

This week:

- AF due Sunday (3 days after brown discharge) and tested negative

- 3 days has passed and took 2 more tests with BFN’s

- mild nausea this morning, extreme fatigue past few days, peeing every hour but I drink a lot of water due to nutrition plan

Implantation bleeding?

Odd period?

What do you think!?