u/FrostingLegal7117

I am finishing up a big tiling job in my kitchen. I am a diy'er, and this was my first tile job. I'm happy with how it turned out, but need some advice on how to finish it.

I have an old house. My walls are not straight or plum. As a result, I have a gap in the corner that is up to half an inch, and in some parts of my ceiling, there is a gap of about 3/8" between the top tile and the ceiling.

What is my best move for filling these gaps?

I have grout-matching caulk that I was thinking of using, but that's a lot of caulk and it's expensive.

I want to avoid grout - my house moves and settles so I don't want to grout any edges because it will crack.

Backer rod to fill then caulk?

Any tips appreciated.

Thanks!