10 DPO strong positive and advanced week indicator

Tia
Ladies ... I'm looking for your opinion. Period started on the 1st, peak on clearblue advanced OPK on the 8th, strong positive FRER on 19th (10 DPO or so I thought), 3+ weeks on Clearblue Advanced today on 22nd. Strong symptoms since the 15th.
What do you think? Did I miscalculate? Am I having twins? Wild speculation and similar stories welcome.