Hey Deep, glad to hear the tournament was a good experience and overall you felt you did ok. I think it’s always good to gain experience by playing these different events and players, it will help you improve. A lot of the things you’ve mentioned here are not uncommon for people to struggle with during games at all. It’s the irregular placement and getting into position combined with the fast decision making that causes mistakes as you said.
With the backhand I would start off training 2 fairly simple irregular drills, the first one is playing forehand topspin into your opponents block and any time they can switch and block to your backhand, you have to try to play a positive shot and then return back to forehand topspins again and keep repeating this. This one is great because you said you feel confident with the forehand and playing strong so it combines a strength with the area you want to improve.
The next drill I would do for the backhand is simply a short serve the opponent can push long either to forehand and then block again to forehand and then free, or the opponent can also push long to the backhand and then block again to the backhand. So it’s working on that 5th ball attack and playing strong but still with the irregular element as you may still have to move to the forehand.
There are of course quote a few different ways to work on this area but I think those 2 are a great place to start!