Top cat, part of your weight gain was getting back to what you were before diabetes, the extra half stone also seems fairly normal after starting using insulin and as you say hard to get off. Hopefully though you should stablise.
I have Lada and after the initial gain my weight has stayed the same for the last 3 years, though I sometimes yearn for my pre diagnosis size 8 figure. If you eat enough for your activity level and take the right amount of insulin for it then that's exactly what it should do.
If you were having lots of hypos it would be a sign that you were be taking too much insulin, which would put on weight ; with a double whammy... as you would also have to eat extra carbs to get out of the hypos and lots of people overdo this
Starting using bolus insulin is less common than starting on basal but I've read of several other people that have started with that regime. There are as yet no clear treatment options for LADA and specialists may well target the treatment at what seems to be the most necessary;in your case post prandial rises. I can also see that using fast acting is more flexible as you're not tied in to the long term action of lantus or levemir when your pancreas 'decides' to produce a bit more insulin as it tends to do with LADA (for some people this can happen for a considerable time)
As for Hba1c, the ADA has recently suggested adopting a cut off point of
6.5% in an A1c for a diagnosis of type 2, between 6 and 6.5 would be considered pre diabetic.
This presentation shows graphically why this figure was chosen (slides 3&4). Below that the incidence of retinopathy usually used because there is more data) seems to be inconsitent (individual variability)
http://www.docstoc.com/docs/15295177/The-Diagnosis-of-Diabetes-The-Case-for-the-Use-of-the-HbA1c