Work for the army, 6 months pregnant with twins, some want me to quit.?

The fact that they are trying to get you to quit means that they can not legally fire you so your job should be safe as long as you don't bow to the pressue, and you follow all the rules and all procedures, and seek the advice of HR (or equivalent) and check up on FMLA (Family Medical Leave Act) on the US Department of Labor web site. The more information you have, the less stressed out you will be.