Hi AvB
The bottom shape between a Go and Carve is the same. There's only about a kilo difference in weight between Go and Carve so it'll have an effect on planing, but it shouldn't be dramatic. Easily fixed with a bigger fin.
I'm thinking that like Ezric said, you need to bear off down wind further than you previously thought possible. Probably 110 to 120 degrees off the wind. Once planing, then point up wind.
Also if you're in marginal conditions, use minimal downhaul and not too much twist. Downhaul tension has a big effect. This is what give the eind range.
Also your fin might be too small. I use the tail width as a good guide to fin length. i.e: for a Go, tail width is around 49.2 cm. So in marginal conditions, I would use maybe 52 to 55 cm fin. Also look at the rake. Pointer fins are good in light winds. In ideal winds, maybe 48 and then in high winds I would drop maybe to a 44. But by then I would be down selecting to a smalled B&J board.
Also try staying a little bit forward of the straps until you're planing.
Also try to coincide pumping with a bit of lift from some swell then getting into the straps once you're planing.
Once you get the short boards going, you won't be looking back..... So much easier than the 90's
Have fun