Remembering baby angel?

Hi I had a miscarriage and want to have a remembrance day or birthday day for my baby angel but I'm not sure what day I would have been due. I thought I'd be due 22 July, went to my 12week ultrasound and lady said the baby stopped growing at 8weeks and 5days and she thought I'd be due in august, so confused on the due date. Or if I should just have it the day the baby was taken out which was in the 16th of January. What would use do ???