Sorry, back now noeyedear, hope I'm not too late for you.
Glucose in your urine is only an indicator for GD. I have GD but have never had glucose in my urine. Having said that, controlling your blood sugar through diet isn't a bad idea for anyone because it puts less strain on your pancreas, which is already working hard producing all the hormones your body needs.
Most GD women are induced at 40 weeks, intervention at 37 weeks or more is only done if baby is getting too big or has other problems (for example, mine has slow growth which may be due to an inefficient placenta caused by GD). Women with GD have extra scans to diagnose these problems but I guess you may not have been offered this. Your midwife should be measuring your bump though and if it is too big or too small should refer you for a growth scan.
Please don't let it worry you too much. You've had two negative GTTs so you don't have GD. I'm going to run you through the risks of people that do so you can see it isn't that bad. Firstly, the placenta may fail sooner, which is why they induce at 40 weeks. The baby may have a bigger tummy, as it stores the extra sugar as fat so may be bigger than normal. The baby may have a hypo after birth because it has higher insulin to cope with mum's higher blood sugar and once on it's own blood sugar that's too much insulin. The best thing here is to feed as early as possible and have skin to skin to encourage and stimulate this.
If you get as far as 40 weeks you could point out your high sugar in urine history and ask if they'd consider induction earlier if it would make you happier.
Now, diet. The main thing is to reduce the speed at which your body turns food in to sugar so that it has time to produce enough insulin to manage your sugar levels. This means that you need to avoid refined sugars. Basically if something is white, beige or sugary be suspicious. So white bread is a disaster (very easy to digest, huge sugar spike) wholemeal bread with seeds is much better. Ice cream is basically milk and sugar mixed with flavouring so that would have caused your high reading. You'd have been better to have a fruit salad (fibre in fruit slows release) and double cream (fat but no added sugar). Avoid white pasta and white rice, choose basmati or brown rice and brown pasta. Eat fruit but avoid fruit juice. The fibre slows the digestion.
Adding protein (eg beans, eggs, meat) slows sugar release. Fat also has this effect (butter, cream, cheese) but if you have a high BMI you might want to avoid high fat options. If you google you'll find lots of advice on GI and GL (glycaemic index and glycaemic load) diets, which are helpful to follow. Diabetes UK also has diet advice.
Do let me know if I can be of any more help.