Are you doing a liver shrinking diet in preparation for WLS/gallbladder removal? (Only asking because it gives more context for ideas/suggestions).
Gluten free pastas are higher in protein if you can allow for them in terms of carb count - you'd need to check the full nutritional information obviously, but they can add a bit to your total and might make a change if you aren't trying to have zero carbs.
Other than that, another vote for prawns, especially if you can add herbs and spices to them to make for some variety (marinade with garlic/garlic powder, chilli, salt, pepper and some lemon or lime juice plus coriander, jerk seasoning, five spice, lemon and thyme or basil, etc), chargrilled squid or white fish.
Turkey is best with lots of seasonings - if you get mince instead, you could make them into meatballs with salt, pepper, chilli, mint and parsley/coriander, perhaps adding cumin and cinnamon/garam masala and then having those with a 0% greek yoghurt, cucumber, salt and lemon dressing. Just bake them on a rack instead of frying.
For something a bit less 'standard', you could try Turkey with Caraway. It's usually used with pork but Turkey would work as well, especially if you paired it with fennel and red onion. If you can work an orange into your fruit allowance, you could add a couple of sections of that into the salad.
And noodles - if you can do glass noodles, they'll soften perfectly in kettle water with a stock cube (if allowed) and you can add edamame beans/peas (frozen in the morning, fine until lunch in the tub), chopped spring onion, dried seaweed and chilli at lunchtime. Maybe add a spoonful of white Miso to the tub and just make sure the water isn't actually quite boiling. Tofu should be fine, too.
If Miso is acceptable, you can also use that to marinade chicken.
Steak is only high fat when you include the fat - lean steak strips if checked, might not be a risk after all.
What about beans? A mixed bean salad (there is a version sold in just water rather than a dressing) could improve Tuna or stand alone with lemon and herbs or mashed with cumin and slackened down with the addition of some chilli, water and lime juice to make a Tex-Mexx style dressing.
And is it all olives or just olives in oil rather than brine? Even using a bit of the brine to mix into tuna would make it taste. Could add in capers or pickles for some extra flavour, too.