The Baby Buddy app from @BestBeginnings is really good. Each week it gives a rough size for the foetus along with a similarly-sized object to help you visualise it.

(and also a creepy drawing of the foetus which you shouldn't look at while eating)

(1/2)

Unfortunately, 'size' seems to mean 'length', with no consideration of volume or eccentricity.

So, in the last few weeks, L-P mk2 has been:

A tea bag 😊
A bar of soap 😐
A tin of beans 🥴
A CD 😬
A pen 😅

I don't think anyone would say those are in increasing size order.