Prison is no joke, and your person has the right instinct. Keeping emotions close to the chest is genuinely good survival advice in any federal facility, not because the place is a warzone, but because showing vulnerability in front of the wrong people can create problems you do not need. That goes for staff as much as other inmates.
That said, the specifics here matter. FMC Carswell is a federal medical center in Fort Worth, Texas, and it houses women across multiple security levels. With a 30-month sentence, she is most likely assigned to the camp, which is the minimum-security portion of the facility. The camp population is generally lower-risk, the environment is less tense than the main compound, and the day-to-day reality is a lot closer to structured boredom than anything dramatic.
It is nothing like what you see on television. Those shows are built around conflict because conflict makes good television. The actual experience is mostly routine, repetitive, and long. That is its own kind of hard, but it is a different kind of hard than people imagine.
The best thing she can do with 30 months is treat it as time that belongs to her. Exercise every day, read everything she can get her hands on, write letters home, and stay out of other people's business. Inmates who keep a low profile, stay productive, and avoid drama do significantly better, mentally and in terms of their record.
She is going to be okay. This is not the worst situation she could be in, and 30 months moves.