Your sister sounds like a wonderful person!!
This reminds me slightly of an interview with Cher I seen earlier today. They asked her about her son Chaz, she said it took awhile to get use to what was happening, as she kept talking she never said her or him....I was getting a bit worried wondering how she really felt. Then at the end she mentioned in her usually sarcastic funny way...."hell I still use the wrong pronouns, but he's definitely a man!! I could completely understand what she meant. I felt vey good for Chaz. It is so hard for people so close to call you the proper pronouns. I have been FT for over 2 years now, my children still call me him quite a bit, it does hurt because they don't treat me like a "him" they're just so use to it. I can't blame them, but I do correct them and say I am not referred to as him anywhere else!!
Your sister is right, your not going to just wake up one day! My transition took over 3 years before I came out and then a little longer before I went FT. I took everything very slow and never marked a day I would do something or remember when I did do something significant. I was even still was working as him after my legal name change....though not for long. I could of went FT a year before I did since I was being gendered female even when people knew my very typical man name, I also stopped being gendered male on the phone even though I didn't think my voice changed that much. This is how gradual I took things. The voice was the biggest fear, I refused to fake my voice for the rest of my life. The thing is I am faking it but it doesn't seem that way, even if I get very lazy and just relax my voice it still sounds like a woman's.
I'm not a big believer of just changing over in one day, I don't think it's fair to the ones that love you. Even when I did go FT I still kept things mellow.....though I' m not overly girly to begin with...but definitely not a tomboy. The biggest noticeable change I made more present was the fact I had breasts, this was very scary at first...since I tried to hide them for the past year!! I didn't wear any low cut tops, its just they were now out in the open!! Beyond that I didn't wear dresses, paint my nails, wear a lot of jewelry, I was frankly pretty drab for a women. I did this so to not shock the ones I loved. After about 6 months of being slightly drab I got to the point close to where I am now....though I still didn't wear any skirts or dresses. I am now at the point where I own 4-5 dresses and the same for skirts but wear them sparingly, but I like the fact I can when I want and do go through stages where I will wear a dress or skirt 2-3 times in a week.
The biggest challenge I have is convincing myself I am nothing of a man any more....I am a woman!! some trans are more secure with their selves even though others may not see them as much as a woman as they do...and quite frankly they don't blend in 100% but they are 100% secure with their selves, I envy them!!. I have had much of the opposite happen, I have had people that found out and don't believe, or people very close to me say the same thing Cher said about her son, even my children do not see me as nothing but a woman, they do still call me dad but they treat me 100% as woman, I have had instances happen that should eliminate any thoughts that I appear as anything but a woman, one that included my ex .....so then why can't I do the same for myself!!
The hardest part of being trans is convincing yourself, its harder for some if others don't see them the same as they do, but then it may be easier since they may be more comfortable being trans....but for someone like me "the so called passable" I can't get over the fact I use to be a man. I think its harder since I don't want to be known as trans...I just want to be an ordinary woman. I realize it's been just over two years but I fear this feeling will never go. I can guarantee not a single cis person goes around thinking "I wonder if they know I use to be a ......". I feel the few small things that still happen don't help, even my sister who has the view similar to Cher still says little things that make me feel like she thinks of me as a man, its not the mis-gendering (which isn't often) its just the attitude certain times. I find that I just don't want to be around anyone that knew me as him, but that's impossible!!
I have heard some say that they couldn't appear as a man if they tried. I don't believe this to be true. I think I could pull off appearing as a man fairly well.....acting I don't know! I do wonder though if I went out as "him" would I pass....I sometimes think I need to try this just to convince myself that I am a woman!!