I am finding perimenopause is playing havoc with my digestion so trying to eat more in the day time and less at night. Other filling lunch foods you may want to investigate are canned pulses and beans. I was going to suggest cheeses too but I'm getting the impression you don't have access to a fridge in the office? Avocado is ok to sit out at room temperature and is full of good fats that helps fill you up...

You could also make overnight oats and take them into work to eat cold if the weather ever warms up enough for that to be appealing! (She says, laughing because there is fresh snow in the local hills here as of yesterday morning)