Reminds me of the first betta I ever got back in 2002 when I was in high school.
And I echo the other members here, in regards to a bigger enclosure. With the setup you have now, you would ideally want to do daily water changes, so a bigger home= less work for you.
Check out this thread for some ideas and inspiration regarding bigger (but not too big) tanks, vases, etc.
You could prob. find something around the house which could work. Old cookie jar, large flower vases, etc.