Another thing that no one has mentioned is that you used settings for 1/2" material, while most, so-called 1/2" plywood, is actually under thickness. Combining under-thickness plywood with your 1/2" settings, 1" screws, and overdriving, your results are pretty much doomed from the beginning. Due to these issues, and the fact that material, unless really well clamped, tends to slide when using a Kreg jig (sorry, but it does have an "r" in it, although a "keg" might come in handy in this build), has caused me to forego its use. I would use my Domino joiner (NOTE: No "t" in "joiner", as it's a tool used to "join", rather than "joint", which is not to be confused with the fact that it's used to create a joint) with 4 mm Dominos and the Domiplate to get the joints properly aligned, and either glue it all together or screw the bottoms up from the bottom and the tops down from the top (countersunk, of course).