Well done so far OP. 3 meals a day, and not horribly unhealthy choices. Certainly it sounds like portion sizes are small, lacking in good fats and probably not a full vitamin/mineral complement but looks like you are probably getting enough fibre and protein at least, and eating regular meals which is fab.
I agree with upping vegetable intake, especially leafy greens (calcium, iron) - side veg, salads or green smoothies perhaps - and different colours of veggies (variety of colours = variety of vitamins) perhaps try different veg to make chips/wedges with - sweet potato, butternut squash, celeriac, beetroot etc.
Healthy fats - omega 3/6 fatty acids - from nuts & seeds, olive oil, avocados & avocado oil, oily fish (fresh salmon, tuna, mackerel - 2 portions/week) if you are pescetarian. Easy ways to include nuts/seeds are in salads, stir fries, nut butters with apple wedges for a snack, nut butters on toast, adding hemp hearts to porridge for example would be an easy way to get a nice level of omegas. Avocado on toast or as a basis for a pasta sauce/'avonaise' salad dressing, or just as a side with a cooked breakfast or 'picky' type lunch.
I'm with you on the not being keen on fruits. I try to get my fruit portions in smoothies, adding dried fruit to granola/porridge (blueberries, goji berries etc), or adding small fruits to salads/main meals, for example pomegranate, grapes, pear, apple or citrus are easy to integrate into a salad without the whole thing becoming sweet. Put apricots into a veggie tagine, sultanas or dates into a curry etc.
As you eat dairy, incorporating small bits of cheese into meals can help up the calorie count, nice source of calcium etc. Tofu is also a good source of calcium.
Keep on keeping on, OP