Rainbow baby!!🎉

so on 2.28.18 I miscarried. @ 4 weeks and 5 days.. I had surgery 5 days prior due to 4-5 inch cyst wrapped around my ovary the dr. said it would twist and kill my ovary and end up losing the pregnancy.to. so had emergency surgery. 5 days later boom. MC.. then 2 months with no period.. 2 months on birth control and bam here we are blessed our rainbow baby!🎉💙❤ my only problem now is teying to figure out the due date.. my cycle was 22 days long before I got preggers.. 4 day period.. but for some reason this app says 3 weeks and 5 days but my other app and other calculaters day 4 weeks and 3 days which seems accurate cus I my test showed up immediately! not even vvvfl.. they super visible and dark I even used a cheapie to see if it was teat or is it me lol . what should I go by 22 cycle days or 28??