BG now 10.5.....no reason for this
Same carbs so same insulin dose.... 2 Units of Rapid... 3 Hrs later....Full on Hypo.....What have I been doing wrong.
Mark, you're doing nothing wrong. Carb counting is a very good starting point, but note that it is just a starting point. If it was a case of just saying X units for Y carbs, it would be a doddle. But there's usually several dozen other things going on in the background which you can't measure which will throw things out.
Personally, when I bolus for a meal, I know that it will generally work out in one of three ways: one, it will be fine, two, I'll go high, so then I take an extra 1 or 2u to bring it back in line, or, three, it'll go too low, and then I'll have a biscuit.
The latter two aren't necessarily failures: I'll have put a lot of thought into how much to bolus for that meal (not just a carb count, but also, where I've been bg wise in the last six hours, what I'll be doing in the next six hours etc.etc), but I know that it won't necessarily work.
It just reflects the fact that T1 is inherently random, and the best laid plans of mice and men gang aft a gleiy... It's a moving target, so if I need to tweak with an extra 2u or 5g after the event, I go with that, just like tactics might change in a football game.
My guess is that you're recently dx'd. Sure, focus on the carb counts, they're the goalposts, but sometimes the goalposts move...over time you'll figure out how to account for the etc. etc. I mentioned above and then tweak the carb count to adjust for those. It takes time, but, in the meantime, treat each "mistake" as a learning experience. Don't just think about the carb count: think also about what else was happening six hours pre and post meal.