first cycle of TTC!

Hey! This was my first cycle TTC. I have a regular 28 to 30 days cycle. I had spotting 3dpo of what I thought was ovulation. Spotting on and off with cramps I get before af, which stopped than. Spotting and pinky discharge on the day AF was due, has now turned to a reddish discharge. I don't know if it's af or not because it's so light. Did the pregnancy tests, a day for the due date and after and were negative.

I'm concerned if it could be implantation bleeding. And if not, what should i take as day 1 of my cycle to calculate the ovulation day of the cycle to come?

I'm 29, going to be 30 soon. how long does it take be pregnant? I don't know why I thought it would be easier. it's sooo frustrating... it's like this is all I focus on!