Did I make a mistake getting a night guard only for my top teeth

I went in to see my dentist at the beginning of February because I was starting to have some sensitivity in my lower teeth (sometimes sharp pain. Sometimes dull pains and it would come and go). My dentist said I was grading down my teeth and recommended a night guard.

I went in earlier this week to get measured for the night guard and after doing the measurements my dentist said they usually only do guards for the top teeth but said that they could do for the bottom teeth as well If I wanted and thought I needed one. I don't know anything about night guards or teeth grinding so I told him whatever he thought was needed was fine. So we went with the top guard.

After looking at some stuff on the internet now I'm thinking I should have gotten one for my bottom teeth as it's my bottom teeth that are sensitive not my top teeth. My top teeth are getting grinded down but at this point they're not sensitive. Did I make a mistake by not getting a bottom guard? Willl the top guard help my bottom teeth?