The situation you find yourself in is one which classical logic starts to have trouble, making this a surprisingly good question despite the downvotes. In classical logic, there is a law of the excluded middle: "A thing either is or is not." This makes logic very powerful at slicing away at problems until one finds a solution. However, in some situations, the law of the excluded middle is a poor model of reality. As you have noticed, "veganism is good" (
good(veganism)) and "veganism is not good" (
!good(veganism)) are both not compelling to you. The law of the excluded middle is simply not an ideal tool in this scenario as phrased.
In these situations, one must be cautious when applying classical logic because it can lead one astray, as you have noticed: it is suggesting to you that you must make a decision. Do you need to be at a decision point right now? Can you reframe the problem such that the problem is no longer unsolvable? In particular, can you reframe it such that you can defer answering the question until new information comes to light.
Donald Rumsfeld is famous for his phrase about the knowns, the known unknowns, and the unknown unknowns (can I call Rumsfeld a philosopher?). The question of "is veganism good" is a known unknown. You know its there, but you don't know the answer. This part has lead you to the stance that you need to be agnostic to veganism. However, when we start talking about not just believing but acting, the unknown unknowns creep in. What if the price of beef goes up (acting vegan looks better)? What if science shows actual issues with GMO soy (making meatitarianism look better)? What if you start dating a vegan? What if your vegan girlfriend suddenly starts eating meat? If you are not fully committed to veganism or meatitarianism, it seems very reasonable that any of these unknown unknowns that come up should influence your actions, while being committed to one side or the other would suggest these unknown unknowns should not influence your actions.
A solution to your conundrum is to seek to be open to new inputs and new arguments, no matter how small they might be. You clearly have not decided veganism or meatitarianism, as per your question, so you should act in a way which opens you up to be flexible to future unknowns unknowns influencing you. This path would make it reasonable to eat some meat, because you need to keep your gut flora ready-and-able to tackle meats if you go meatitarian, but it also suggests spending days as a vegan. Do this not to be a vegan, but to better understand what life as a vegan would be like if you chose that path. Explore vegan recpies. Some of them may taste good to you, and then you should eat them regardless of your final decision on veganism! Be flexible enough so that, when you finally arrive at a choice about veganism, you are fully prepared for whichever path you take.
Many people I know have explored such a middle road. One destination it may arrive at is flexitarian. Flexitarians typically eat vegetarian, but they wont let it cramp their lifestyle. If they are at a restaurant with friends and cannot find vegan fare (an unknown unknown), they will eat a meat dish so that they get food, and they typically will not make a big fuss about it so as to not disrupt the meal.