conceiving whilst bf a nearly 2 year old- advice for tracking cycle

Hi all, have any of you got tips for tracking your cycle with the aim of identifying the fertile days whilst bf and ttc?
My first born boy is 2 next month. We now want to ttc #2 and I am still bf with a fairly regular cycle give or take 2 days. I know bf messes up your bbt and I am still getting up in the night at least once for my ds which will further reduce the effectiveness of monitoring bbt so what is the best way to track cycles that have worked for you if you have bf whilst ttc
Tia