Grab a new 7m now and head on down there to jump sharks!
5m gap is too much. Maybe fine between your extra large kite and your big kite, but not when going down from a 12m. 3m is the right call unless your going to stick with a two kite quiver in which case you can stretch to a 4m gap max. Peter has kites in 1m increments! There is so much wrong with a 12/7 quiver for any kiter let alone a novice. First, a 7 is a super fast kite that can kick your ass in a heartbeat compared to the sedate pace of your 12. You set yourself up for a spanking by jumping straight into small kites in high winds. I have known pretty good kiters who took a few years to get down to that size. The water conditions alone are often intimidating to novices. Second and perhaps the most important, is that a 12/7 quiver will never see you on the ideal size for the sweet spot of the sport.........20-25 knots aka 9m weather. Super fun, but not off the chain....... 12/7 and your either hanging on poo stanced, kite trimmed in all the way and flying like crap, or having to whip the kite around like a mad man struggling just to hold your ground and unable to jump.... Either way, frustrating and potentially unsafe, especially in waves.
The next logical step for you is a 9m.... I know you wanna cover a certain range..... all the way up to 32
but you are falling for the silly game the marketing department has devised. Lets just say its not really worth going over graphs compulsively while you fall asleep. What matters is comfort and safety. better to miss out on 7m weather until you are comfy on a 9, than to go with a 5m gap and set yourself up for frustration or worse in the best conditions your trip will offer.
You already own a large, your next kite down should be a medium, not a small. You need to spend some time on the medium in its associated conditions before you'll get any utility from a small. Maybe your really talented and will move on to a small in no time, maybe not, but if your asking questions about a 5m gap, referencing graphs and what the light grey really means, you have little practical grasp of what 32 knots is actually like.
Get a 9 and go down there and see what you can do and learn. If you feel your missing out, you can likely rent or score a used small kite down there.