help with BBT

Lindsey • 20, married, and TTC for 1 year
I don't know what my chart means so far 😬 First month on a high dose of Metformin + Actos. The bleeding on my chart was actually mid cycle bleeding that was essentially just a light period. Not sure if I'm on cd30 from my last cycle or if I'm mid cycle again from this light period!! Lol. Any advice? What does this dip mean?