I made this bag recently too. It is such a lovely bag, I really really like the material I chose, just right for Summer.
The topstiching reuires you sewing through approx 8 layers at one point (6 cotton layers from the outer bag, the lining and the handles plus 2 from the interlining) – my machine struggled big time. If I did this again I may shorten the interlining and then stitch 2 lines of topstiching to secure the interlining and handles at the top.
Beautiful bag though even though I say so myself!