There are unhappy and happy people from all walks of life and situations.
Personally, I am not full time or anything yet, but even working towards my goals slowly I feel very happy about things. I don't anticipate transition to end all my problems, after all I am still me, and I have problems unrelated to it all, but I am very confident in the quality of life improving. Even now, just telling those around me how I feel has already made me a happier person.
And to be fair, what does your dad know? I mean, I have my doubts that he is some expert who researches transgender people's happiness, and if he isn't an expert in the field he is just another person with another opinion, an opinion that is likely based out a desire to protect, but still not one that is more informed than anyone else's opinion.
What I am getting at is this, I married a African-American woman, a few people told me some pretty crazy stories about how interracial couples get attacked, harassed, etc. They were trying to protect me, but the truth of the matter is they have no clue what they are talking about, 7 years later and the things they mentioned have yet to come to pass. Basically, even well meaning people can worry themselves into saying things are aren't true based on their perceptions of reality, and I don't doubt some couple somewhere is getting harassed, but certainly no majority.
The point is, doing what you feel is right is the most important thing, everyone loves to make up stats and generalize to try and keep other people from doing what they want to, sometimes they even mean well by it.
