You didn't mention the Line and Load connections on a GFCI receptacle. When there are only 2 conductors, not including ground, connect to the Line side as you did. There are no positive or negative wires, the black wire is hot and the white wire is neutral. A 20 amp receptacle can only be used on a 20 amp circuit with 12 gauge wire. It looks like that, if so you're ok there. A 15 amp receptacle, like the one you removed, can also be used, as a 20 amp is unnecessary.
Thanks for the helpful info
You didn't mention the Line and Load connections on a GFCI receptacle. When there are only 2 conductors, not including ground, connect to the Line side as you did. There are no positive or negative wires, the black wire is hot and the white wire is neutral. A 20 amp receptacle can only be used on a 20 amp circuit with 12 gauge wire. It looks like that, if so you're ok there. A 15 amp receptacle, like the one you removed, can also be used, as a 20 amp is unnecessary.
The old GFCI looks like a 15 amp receptacle
Your right, but the 20 still works.