Go for a biostat master or position after getting a applied math and stat master?

I have an applied math and stat master degree and a biomedical engineering master degree. I didn't learned many statistica methods though nor biostatistics, but more on probability theory, stochastic processes,statistical theory, classification and optimization. My research experiences are using some machine learning algorithms to solve some proglems in psychology and computer vision, one project using classification in bioinformatics, some kalman filter's error study, stochastic differential equations.

I havent applied many jobs yet, just 8 also. but I got no news but some rejections. The jobs I applied to are all biostatistician in nonprofit educational universities and government agencies (because I am foreign student, not continuing with my PhD, and need a non-profit H1b working visa).

So let ask two questions:

How difficult is it like to get a biostatistican job in my case?

is it bad to study for a biostat master after getting a applied math and stat master?