First timer - understanding 'x weeks', vs gestation, vs being in the 'xth week'

[woollymammal99]

Sorry for the dim question!

I'm trying to understand what I'm reading about each stage on my tracker app What to Expect. Right now it says I'm in week 5, and I'm at 5 weeks and 2 days. Each week it gives me details about what's happening this week - so is it giving me details now about what's happening in the sixth week? I hope this makes sense! And likewise, if I'm in week 5, am I in week 3 of gestation, and the processes of the 4th week of gestation are underway! Please help my tired brain to understand XD I'd appreciate anyone's insight, thank you!

IME everything just goes on weeks - so you're 5w 2d, so look up everything that applies to "5 weeks".

When you've had your 40th birthday, your refer to things for 40yos, you don't talk about being in your 41st year. Same thing.