What week am I really?

So I’m supposed to be 8weeks today BUT my mum says I’m actually 6weeks

On a <a href="https://play.google.com/store/apps/details?id=com.glow.android.nurture">due date calculator</a> it’s goes by the first day of your last period (everyone know that’s) which mine was 27th April

Which puts me at the 8weeks mark

My mum says that because I conceived most likely on 11th may that makes me 6weeks

But the pregnancy+ app says 8 and I can’t change it🤷🏽‍♀️ I’m very confused

I’m waiting for my first ob appointment 🌝

Is the pregnancy+ and internet right or is my mum? Because I know doctors add two weeks on but I want to believe I’m 8weeks...makes me feel happier 😂