Hi!
Firstly, I have to say congratulations on the weight loss. That's pretty amazing and you should be very proud of yourself, I bet your kids are proud of you
Anyway, some random advice. Have you tried making the porridge with water instead of milk? I don't do cereal, so I can't vouch for this personally, but I'm told it doesn't taste much different. But I read something ages ago that said certain chemicals in milk can raise your blood sugar more and faster than you would expect from the carb count.
Regarding potatoes, the more processed they are, the faster acting their carbs will be, same as all starchy carbs. This is basically to do with processing and cooking of foods breaking the sugars and starches down into shorter chains, which means your body breaks them down into glucose really quickly. So boiled potatoes are best really. Baked potatoes can be a nightmare. Apparently sweet potatoes absorb slower than normal ones, might be worth a try. A book about GL diets might be useful as a guide. GL (glycaemic load) can be more useful than GI values. This is because GI is measured by eating 50g carbs worth of each food and then measuring effect on blood sugar. So it doesn't take into account the fact that it's really easy to eat 50g carbs worth of cake, but more challenging to eat 50g carbs worth of cabbage (that's about a skipful). GL does take that into account so it can be a helpful guide.
If you want to eat bread, have you tried Nimble? It's silly little slices of diet bread, but it's ok if you just need a quick bread fix. If I eat normal toast for breakfast, I need to do extra insulin, but if I eat Nimble, I tend to go hypo. So I'm guessing it might be good if you're trying to cut down carbs. Also, pulses such as chickpeas and especially yellow lentils are meant to be very slow absorbing carbs, and will also add low-fat protein to your diet, which will help you feel fuller.
I'd be inclined to cut down on sausages or only buy the pricier ones with a decent meat content. God knows what really goes into sausages, but they can have a surprisingly high carb content (although I suspect the cheap ones are mostly sawdust, no idea what that does to the blood sugar!). Also may be worth cutting down on diet drinks. I think there's some divided opinions on the effect of sweeteners on blood sugar, and also I read something recently that suggested that drinking something sweet puts your body on alert that it's going to get some calories, then when it doesn't get what it expected, it effectively goes into starvation mode so you retain more calories from your next meal. I don't know if this affects blood sugars though. I just can't take the taste of sweetener so I don't bother.
Oops, sorry this is rather long. But hopefully one day someone will benefit from my wisdom/ random bletherings. Anyway, my final and most important bit of advice. DO NOT EVER LET THE DOCTOR MAKE YOU FEEL GUILTY FOR ASKING FOR STRIPS!!!! They have absolutely no right to make you feel bad. You need the strips in order to have a healthy life. And whatever it costs the NHS to provide strips, it'd cost them a hell of a lot more to treat you for the numerous complications you could develop if you don't get to test as often as you need to. So if they question the number of strips you get through, tell them to shove it. Anyway, who cares what they think of you personally? Sorry, this rationing of strips is my serious number 1 pet hate. All through my childhood I was told off for not testing 5 times a day. Now they tell me I don't even have to do it once a day. Yeah, right!
Anyway, hope some of that is useful... Keep up the good work!