Ttc after miscarriage?

My husband and I are ttc. I found out 2 weeks  ago I was pregnant and then last Sunday had a miscarriage. 😢 my body took care of everything on it's own so no d&c. My doc said we can start trying again right away cause I was barely 5 weeks when I miscarried. My question is, how do I know when my fertile window is? I had stopped taking my bbt so I have no idea what the trend is. Am I just going to have to wait until I get a period and go from there? Thanks!