You can hide your breasts by binding them with a tight undershirt, and be on HRT for as long as you want without coming out. You will look more youthful, and will have better skin, so you may get comments about that, but no one will probably notice that you are transitioning, unless you do things like growing your hair and nails, dress femininely, speak femininely, walk femininely, get electrolysis, have your ears pierced, and do other things that call more attention to what you are doing. The effects of HRT affect our psyches more than our physiology in the beginning, and we tend to think that we are further along than we actually are. Even if someone notices your breasts they will probably think you have moobs. I'm not telling you these things to be a "Debbie downer", I'm sharing my personal experience in hopes that you do not come out too early and upset your life, and lose your job like I did (because I followed bad advice from a therapist) one time before I actually went full time a few years later.