How do eggs burden your liver? Is he referring to the protein content, which would seem strange given your problem? Is your cholesterol already high? This is usually a symptom of something, rather than anything to do with dietary cholesterol. Are you consuming over 50g/day of carbs? If you’re in ketosis and eating low protein, you’re literally wasting muscle by the hour, because it’s your main source of glucose. You need at least 600-calories/day from carbs + protein to avoid wasting. I’d aim for at least 200 from each and balance it in the way that feels best/most convenient.
Seeds are a bad source because they’re packed with omega-6s. Same with most nuts. Sources like quinoa, oat bran and buckwheat come with a lot of starch and aren’t as bioavailable as animal protein. All plant sources have drawbacks like phytate and phytoestrogens, so make sure you prepare them thoroughly and keep them varied.
Gelatin is good to add to sauces/soups. 9g has about 7g of protein like an egg. Kefir has over 3g per 100ml. Do you tolerate dairy? 1-2 glasses of kefir, 10g gelatin, 2-3 eggs and rotating plant and animal/fish sources should allow you to push way over 50g/day.
You could look into supplements, but wholefood protein sources tend to be full of valuable nutrients. The fact you have a protein deficiency might suggest you haven’t been obtaining many of them (fat solubles and B vitamins esp B12 etc), although I suspect it has more to do with the low-protein and low-carb diet, two things that should never go together, unless you’re Arnold Schwarzenegger and want to lose 100lbs of muscle.