Deleted an Upgrade on Skyrim

Sounds like the decoration status of the room got reset for some reason. One thing you can try is go back to the Jarl and see if you can buy the decoration for the room again. Given that there are quite some bugs in this game it is quite difficult to tell you what exactly happened to answer your question.

What I can recommend you only is to try to buy the decoration again. If that fails, it might be stuck in this status unless you start working with console commands to fix it. You can use the console commands also to get back your mask.

Ok. In Breezehome, there are 2 beds. Your master bed, and a followers bed.

In most other houses, the same thing applies so make sure you have 2 non-owned beds not including the master bed for your children.

Second, if you own the DLC houses, you may want to build a bedroom addon as well as the main halls 3 beds. Because you can obtain a Bard, a Housecarl and a Steward, thats 3 beds taken already. It's basically all based off of free beds.

And 2 children is the limit as-well.

Also, you said you have 2 beds taken up and only one child. Its because your housecarl owns one and Dorthe most likely owns the other.