Where to see my full Apple purchase history

On a Mac you can also open the Music app or App Store > Account Settings and scroll to Purchase History, it's easier to read on a big screen. Searching your email for 'receipt from Apple' works as well, they send one for every charge.

On the iPhone: Settings > tap your name > Media & Purchases > View Account, then Purchase History. You can filter by date there. Subscriptions are a separate list under Settings > your name > Subscriptions. If it still doesn't match, check whether you're the organiser of a Family Sharing group. Purchases by family members get billed to your card and that's the usual mystery charge.