You're not doomed to gain no matter what. Don't worry; little mini-plateaus like this happen ALL the time.
When I'm stuck on a plateau no matter what I do, it's usually because I'm retaining water from my cycle. Remember, too, that weight loss is not linear. Our bodies are complicated things that any number of variables can affect, from the things we expect (like food, water, etc.) to things we don't (how much sleep we got the previous night, our stress levels, the weather, etc.). Our weight also tends to move surprisingly little based on the choices in the immediate 24 hours. Instead, they tend to ride the trend of our choices over a long period of time. So eat in a deficit, exercise, drink lots of water, watch your cycle to make sure it's not because of that, and you'll lose weight just fine.
I'd also recommend taking measurements, since the scale can be such a liar, measuring not just fat, but our bones, organs, and yes, water weight. The tape measure is much more honest.
I do feel obligated to note that I see you're trying to lose to a BMI of 18.5. Just be careful, okay? That's pretty low.