Am I going to gain weight after eating this today?...?

NO you won't gain. So of the cals you gave they totaled 820, plus whatever cals were in that dinner which doesn't sound like too much maybe 350 or so, so somewhere around 1170 cals for the day........um you should eat more cals in my opinion. Eat too little and the body starts eating away at your muscle which is a big no no. I'd suggest 1400 cals a day. It may seem like your eating a lot cause 7 rice cakes and 5 cereal bars seems like your constantly eating something, but what your eating doesn't amount to much real nutrition for your body. Like eating tons of lettuce, you may be eating non stop, but your body isn't getting squat. I'd sub out some of those rice cakes and bars for other treats like some steamed veggies, other fruits or something with carbs and then also bulk up your breakfast. You need to start the day right, and just a shot of espresso doesn't cut it. Maybe eat eggs, or fruit, heck even eggos are pretty healthy for you honestly. And now I must ask....why are you trying to lose weight? At your height, I'd actually say you should weigh more than you do. I was 5'4" and 118 lbs and quite the skinny thing! (just had a baby so that's long gone lol). I think your a fine weight and you should actually be eating to maintain it, not lose more.