I don't agree on your analysis of sentience. The term sentience has no concrete meaning, so how can you base your moral judgements on this? Plenty of plant life has senses and are able to "feel" things.
If something (living or not) cannot experience suffering then you can’t harm it, by definition
This follows no definition of harm that I am aware of, and I do not agree with it. If you are not aware that you have been harmed, you are still harmed. So you should also be able to be harmed even when you could not be aware of it. Therefore, I do not accept this sentiocentric (just learned this word) argument.
There are good reasons to treat different beings differently but they should be based on the beings’ interests, not their species
And this is one of those reasons. A human's (or any other animal's) continued existence is mutually exclusive with the food's continued existence. If we do not follow speciest dogma, we might as well eat other humans.
This argument also implies that "dominionism" is wrong, i.e. all life has a right to not be killed or abused. Yet human life is impossible without killing and consuming other living organisms, be it plants, animals og fungi. Thus it is unethical to continue living.
This argument is bad, because for human life to be possible, you must draw the line between life that you consider ethical to kill and life that you consider unethical to kill.