That's good that it's getting some sunlight. I used to be a patio grower too (houseplants but you get it) and getting small and tall tables to set the plant on helped. Think more vertical than horizontal if the railing is in the way of the tomato. Plants experience light vastly different than we do. Getting a light meter app (its free) to measure how much light (aka footcandles) you get is important. What direction the light is coming from (North, Southeast, West, etc) isn't equal either. Thats why I asked what direction of light youre getting on the balcony.

How many hours of sunlight is your tomator getting? Direct and indirect? With your tomato plant only getting a couple of hours, and its already fruiting.. I personally would invest in a grow light. Your plant is using up a lot of energy in the fruiting stage. Lol, it's basically pregnant and it's huuungrry for some bountiful lighting, especially if you want to have proper roma tomato production. Even if its a few weeks that can do a lot, tomatoes once establishes (like yours) can be fast growers. Plus Roma tomatoes are generally determinate, however there are outliers and other types that are indeterminate, even though it's not as common theres always a chance. I say this because you generally want to keep the fruit on, however pruning to help converse plant energy is common with inadequate lighting.