If you're pre-diabetic now, this is the time to get on top of it. Think of it as an early warning system. You don't have to go OTT but you do need to be sensible, by cutting down on the carbs, but not drastically. Diabetes UK recommends less than 130gm carbs per day, but a lot go much lower. I experimented from 90gm, to 75gm, to 50gm, but began to feel ill. My body is OK on around 90gm per day. You do need balance and to get the essential minerals and vitamins. Also it's very easy to become obsessive about finger tests without fully understanding what they mean - that's also what I did. Finger pricking is very useful to show you what foods spike your blood glucose, as you've already learned, but the HbA1c test shows the average over 8 - 12 weeks and is considered a better overall guide. Monitoring does of course become essential if you are on certain medications to manage full diabetes, but you're not there.
I thought my diet was OK, but it was carb heavy. I was advised to cut out the obvious stuff - cakes, biscuits, sweets, sugary cereals, fruit juice, pastries, processed food, ready meals, takeaways, but the occasional treat was acceptable. (Nobody's perfect and I have the occasional strip of 85% dark cocoa chocolate or a small packet of crisps - just not every day!!) Then I was advised to cut right DOWN on bread, potato, rice, pasta - to have wholemeal versions where possible and if you can't cut them out, to have SMALLER portions (a slice or 2 from a small medium-sliced wholemeal loaf, half the recommended portion size, or 2 small new boiled potatoes). There are plenty of substitutes out there - cauliflower or broccoli rice, Bare Naked Noodles, boodles, courgetti, squash lasagne and the Forum has some imaginative cooks. Also fruit should be fresh or frozen, and limited to no more than three 80gm portions per day (that's not a lot when you weigh it out).
I don't know if you cook or have a partner that does, but with a bit of planning you can batch cook and freeze in advance. And you can prepare a healthy packed lunch for work. Depending on your job, I suggest you should aim to get away from your desk at lunchtime, and go for a walk - round the block, round the car park, whatever is available. If you are physically able, also to try and get back into suitable exercise. When I worked some of us went to a lunchtime exercise class, and some for a 30 minute swim. These days, with lunch breaks being so drastically cut, I don't know if that's still possible! It's possible to exercise at home - I have a mini exercise bike, or to do some exercise on your way home. And do something healthy on your days off if you can. I believe exercise helps with depression, and I certainly found on testing after getting out of the pool, my BG dropped to below 7, which was very pleasing.
I'm sure others will add to my suggestions - I hope you work out an eating plan that suits you and reduces your BG.