Struggling to diet with type 1 diabetes

jerseyboss

I've been a type one diabetic for a very long time and I have to make sure I've eaten enough so I don't have a wobbler but I must admit I'm struggling and I can't work out why.
I work long hours and I walk to and from work each day I'm in which is approx 7miles a day in total .
I was getting a lift off a colleague but decided to start walking again after a long time not doing so and I've started dieting after putting on a lot of weight but the thing is I'm eating the same things at work so it doesn't get confusing and saves time preparing different foods to take and for the past three weeks I've been fine but the last few days I've started to have an hypo so ate a couple of mars bars to bring me round and later in the day I felt the same again.
My diet has gone to pot the last couple of days but I can't understand why if three weeks ago it was fine,
I'm now adding more food to certain break times to see if it carries on. Are there any other type1 diabetics who struggle to diet and have any tips.