Never finding the perfect bag I've made my own. Several years ago I made the "Laguna" bag which is a pattern from Quilter's Dream.. I added inside and outside zip pockets and custom pockets inside. I literally loved it to death as one day I realized it had LOTS of wear. Oh, and one day early on someone asked if I made the bag and when I replied "yes", she said "I thought so". This was because, I suspect I used batting for the sides.
So to replace the bag I wanted the same size 11x16x3 but I wanted it to last longer than the several years of my old bag. ("my old bag" sounds funny). I used the same basic pattern but, after looking at the areas of greatest wear, made the handles out of a nice vinyl which I also used for the bottom corners (copying from a bag called "The Everything Bag" from Connecting Threads. I used better fabric as I no longer buy fabrics from Connecting Threads, used Annie's Soft and Stable to line it, and added a zip top closure following directions online similar, if not, https://so-sew-easy.com/sew-a-recessed-zipper-on-a-bag/. I again put in an outside zip compartment, one inside to hide my wallet and loose money, and custom pockets inside tweaking what I had done before.
It took me a while to finish but I'm glad I did. I'm hoping that there won't be an issue with not putting the vinyl at the very bottom of the bag but my old one didn't show wear there so that should work out well. The longest part might be the planning as you want a bag that is the right size for you. So I'd say start with a favorite bag and go from there. When I made my first bag I wasn't sure that it would be so perfect, I thought it would be too big at first but it turned out to be the right size for putting a book or ipad in it which was a consideration for me. I don't carry them around unless going to an appointment but it's nice to know they fit. If I can figure it out again, I'll post photos.