Beta, ask your mother or MIL if you don't remember your last period date. Usually, we count from the day your last cycle started. Take some warm milk with saffron and just consult your doctor for a proper dating scan.
Haan, simple hai na, last period jis din shuru hua thha wahan se weeks count karo. Par best toh doc ka ultrasound hi batata hai exact size dekh ke. Tum chinta mat karo, sab normal hoga.
If I can remember my own name right now, I think you just count from the first day of your last period! Gynac will also do an ultrasound to confirm the exact week because baby growth is the real test. Honestly, those app calculators are sometimes way off.
I only know that my doctor calculated it from my LMP, which is last menstrual period date. My scan also showed a slightly different date. It's best to ask your gynac to confirm the exact week during your scan.
Please get a proper dating ultrasound done at a good clinic to confirm the weeks. After my past experience, I realized online calculators can sometimes be confusing. A doctor's scan gives the most reassuring and accurate details.
I just used an online calculator while eating my favorite chocolate ice cream! But my doctor changed the weeks slightly after the first scan. Go by what the ultrasound says, that is the most accurate.
The standard clinical way is to calculate from the first day of your last menstrual period. But if your cycles are irregular, the first-trimester ultrasound is the gold standard for dating. Don't rely solely on apps!