red meat's not really that good for your health tbh and many reputable health institutions [havard school of health and nutrition, for example] say that you should actually cut it out of your diet, as it highly increases the risk of certain cancers, such as colon cancer. [you can read more
here.]
i'm assuming you're anemic or really need the iron? if you can't readily absorb iron and really need it from an animal source [heme iron], the best source according to
this page is liver; however, as i understand it, liver can be toxic to eat in anything other than low quantities [after all, what does it do?], so duck would appear to be the best choice if it is at the higher end of the scale.
if you can absorb non-heme iron, there are many good choices - cream of wheat, oatmeal, and a lot of cereals are often both palatable and easy to customize [so you can add things to it that you enjoy eating, like fruit, which are always good to eat unless you eat a whole crapton of it - but that goes for virtually anything]. fruit in particular is great to have alongside it, as vitamin c helps the absorption of iron.
tofu is also an excellent source, but you need to know how to cook it - if you don't cook it, it tastes like crap because it absorbs the taste of what it is cooked in - as such, it is one of the most flexible foods in existence. soybeans are actually a complete protein, which means they provide all of the essential amino acids that your body needs.
i would usually recommend vegetarianism on account of it often providing many health benefits when compared to an omnivorous diet of similar quality, but it seems that your diet is quite limited as it is [though such a diet is not as limiting as people seem to think, but i digress]. however, considering that most of your favourite foods seem to be fitting in that category, perhaps you might give it a shot? worst that can happen is that you really don't like it.
whooo sorry for the text wall i just have a lot of old nutritionist information in my brain [i was really into it when i was younger] so that statement just jumped out to me and i figured that i could give you some advice.