The sugar free squash is ok. If you're getting readings consistently in double figures, you either need to cut the carbs even more, or go onto medication. I'd have thought metformin was a no-brainer for you. Safe and helps against future cardio problems-providing, that is, there is no medical reason why you shouldn't take it (kidney probs etc) It won't do a lot to reduce BGs though, so you may need more meds on top.
Are you sure about the 75 grams of carbs? Don't wish to insult you, but some people don't realise just what some foods have carbs wise. One person said they ate only a few carbs, but had loads of fruit and veg! I'm sure it won't apply to you, but do check just what you are eating. Your current levels do look too high.