Transgendered people have the same needs and rights as everyone else, and this includes the restroom. Your mere presence in the ladies room is not grounds for a complaint, if you are using the rest room for its intended purpose. In our company, transgendered people generally have the right to use the appropriate rest room.
Many companies recommend that transgendered people use the restroom matching their current gender presentation. This recommendation is not quite a policy, because in some cities or states there may be a local law that must be respected. Most localities do not have laws governing which restroom people use on private property, so it is likely that our recommendation will apply in your situation.
Do not surprise people by suddenly using the new restroom. Always work with your management first, consulting with corporate HR/Diversity as needed, to establish which restroom is appropriate for you to use. Make sure you have the support of your boss ahead of time.
Always use the restroom matching your current gender presentation. Be on your best behavior, to set others at ease. Any attempt to peep, be lewd, or create any disturbance, by any transgendered or non-transgendered person, in any rest room, may be considered sexual harassment and grounds for disciplinary action.
Go the extra mile to smile and be nonthreatening, if others are present. Be aware that scowling and lack of eye contact can be considered "creepy" and make others uncomfortable. Be on your best behavior. A single complaint of inappropriate behavior in a rest room could result in other transgendered people losing rest room rights, and going back to limiting liquid intake and long trips to other facilities to use the rest room.
It is vital that, if you use the ladies room, you avoid any behavior that might create a disturbance. Fortunately, there are private booths available. Use the facilities with the door closed and with your feet pointing in the right direction. Do not peep or do anything other than empty your bladder. It is OK to wash up and fix your face in the mirror when you are done. If there is a line, or you see other women there, say hello and chat, just like other women do.
If you are presenting as a man with one or two "over the line" instances of gender expression, such as styled hair or a skirt, use the men's room. This means, by the way, that sans any other change, men in kilts use the men's room and women in pants use the women's room.