My balance dropped more than I sent: where did the change go?
After paying, you check your balance and it looks like you spent more than you sent: the change isn't visible.
**Change from a payment goes to a new address in your own wallet, on the /1/ branch of the BIP-44 path.**
Change doesn't go back to the same address
After a payment, your wallet creates a new address to receive the change. That address belongs to the /1/ branch of the BIP-44 path, the change branch. That's why the balance doesn't show up as 'change' in the address you used to pay.
The source BIP-44 (change chain) defines this derivation: change moves to a separate chain from the addresses you show to receive.
Why your balance looks smaller
If your wallet doesn't add change addresses to the visible total, you see less bitcoin than you expected. The money didn't leave your control: it's in an address that is also yours, just different.
Some wallets show all derived addresses, others don't. If yours only looks at receiving addresses, the change stays hidden until you look for it.
How to find that change
In most wallets, the total balance already includes change. If you don't see it, check if you have an option to show change addresses or 'coins'. You don't need to touch your seed: the control is still yours.
It doesn't mean you lost the coins
That the change sits in a new address doesn't guarantee your wallet will show it right away. You might have a wallet that only watches the external branch, or a sync problem. The fact only explains where the money went, not why you can't see it.
Source: BIP-44 (change chain)