Vaginal ultrasound and LMP due dates differ....

Hi ladies,

This is my first pregnancy and I tried to learn my bit from google and it terrifies me.

I had my last period on 7th March 2019 and usually my periods are like 32-33days long and that cycle I tracked my ovulation and got positive on ovulation tests on 25th March and 26th March and a low positive on following 27th and 28th. So most probably i should have conceived on 25th or 26th.....I had my first ultrasound yesterday and baby measured 7weeks 2days and has a heart beat of 172bpm.

And the lab technician dint say anything and said doctor will see me in next 2-3weeks...

I am little confused about the dates, according to my doctor i should be 8weeks 4days yesterday as they calculate from LMP and my <a href="https://play.google.com/store/apps/details?id=com.glow.android">glow app</a> says i should be 7weeks 6days yesterday as it calculates by taking my cycle length and ovulation date where as my ultrasound says 7weeks 2days...

I am really worried if my baby is doing okay... Is it fine to be off my 4days according to conception date and by a week according to LMP...

Had anyone been here and its totally okay or I am the only one who is worrying without a reason.