A bit surprised that some of your friends would have a problem with it.
I don't know that many Dutch people in their 20s who are still that backward. But then again I live in the Randstad.
I don't think feeling happy is a switch you turn on. Or a state that even exists. Coming out was just the first step, eventually you get used to it, and you worry less, you think about it less. And that will make your life a lot more comfortable and unrestricted.
Definitely! There is that initial "weight off my shoulders" feeling which is just amazing but then after that there's the whole process of becoming more comfortable, as you say. So it takes a while but as long as you are surrounded by people who love and accept you for who you are, then it should eventually become much "easier" and the happier you will feel in yourself.