Nursing & maybe pregnant. When to test?

I have 18 month old I’m still nursing. We’re not trying but also not preventing it either.

Im not sure when I ovulated. Im going off last time we had sex before before my hubs had to leave for Business trip.

Going off the 6th I should start by on the 20th. I took test yesterday ( I think that would be (12dpo) it was negative. My question is could I still be and it be early? I keep see all these people getting BFP at 9 and 10DPO. Im completely confused.