If I had my last period on the date when would my date of birth be?

Hello, my period was always every other month for about 5 days. The last day of my period is July 30, 2024. Please give me some information if you know anything about this. My doctor unfortunately miscalculated because there was a month between the appointment and the ultrasound, and everyone said that's unusual and can't be right, but she said it's fine. Please give me some advice and which week exactly would I be now (I'm told a different week for every examination and somewhere else).

And by the way, what helps against heartburn when eating, constipation and a pulling sensation in the left stomach when walking?

I'm asking here because unfortunately my doctor doesn't have much time to answer questions and help isn't possible so quickly otherwise. However, I'll speak to a doctor as soon as possible who knows about this and has time, I hope.