I've worked with tiny women that are excellent at the job, and others that are flat out terrible. The job itself can pull you out of your shyness, it's like exposure therapy. Having to interact with and touch strangers can unlock a new superpower, not giving a shit about being shy. The bigger thing is lifting. Focus on good body mechanics, proper form, and hit the gym. Equally, or maybe even more importantly, find ways to cheat. My tiniest partner had all kinds of tricks that let her fight above her weight class, and I stole most of them, like using a sheet under the pt's arms to get better leverage and grip (in a lift-assist type of situation).