3months ttc off the pill advice

ttc#3
Hey everyone new to this and looking for some advice I've been off the pill 3months now and ttc.
My periods have regulated in to 26/27 day cycle and normally my period is 4/5 days this month it was just 3 and 2of the days were really really light.
I know I ovulated last month as used opk and charted bbt and both a positive opk and an ovulation bbt dip appeared wishing 48 hours of each other.
I'm just wondering why I had such a short period please help shed some light thankyou.