English is for the most part lacking in highly specific idioms however one of it's strengths is that general idioms in different context can be quickly adapted and understood by native speakers.
User Josh61 ultimately gives the most specific idiom with the same meaning as yours with bedridden. However, this doesn't have any of the humorous overtones you were looking for.
Therefor, I would propose the following adaptations of 2 general idioms, (I've actually used both) that convey the same meaning when used by a sick person.
The first is Good friends.
These last couple days my bed and I have become good friends.
This suggests you've spent lots of time in bed but you're taking it in stride and can laugh at it.
The second would be Overly acquainted.
I've become overly acquainted with my bed this last week.
This suggests the same thing, lots of time in bed, but in a more annoyed and sarcastic way.