I bought a really big picture even though I don't have a big place to hang it.
I bought a pretty big picture, but as you know I don't live in a very big place.
この場合、次のような言い方ができますよ。
ーI bought a really big picture even though I don't have a big place to hang it.
「絵を飾る大きな場所に住んでいないが、とても大きな絵を買った」
ーI bought a pretty big picture, but as you know I don't live in a very big place.
「かなり大きな絵を買ったが、ご存知の通り、私は大きな家に住んでいない」
ご参考まで!