App VS ovulation & implant bleeding date


Hi! 1st baby! Just curious,... the app tells me 4 weeks and 5 days (March 11th first day of last period) but if I go by when I had sex during ovulation (March 24th) and when I had implantation bleeding (April 4th.) Seems like less time? Does this make sense. Have my 1st OBGYN appt April 19th. Thanks for any insight!