Your post was very long and informative, so I feel obliged to write a similarly long one in response.
Well, first of all, I'm from Singapore, although I have mostly been in the US for the last 5 years, and had virtually all my experiences, sexual or romantic, there too. (Which is not to say anything about the gay scene in Singapore; I must make it clear that it's just me.) I must also remark that I know nothing about lesbians, so everything I say applies only to gay men.
I think you romanticise things in the West a little bit. Things like PDAs would only happen in big cities like NYC or SF, and even then mostly in the gayborhoods. It's true that people can in general afford to be more open there, perhaps they are further along in their evolution in thinking of sustainable gay relationships, but the "turnover rate" in the US seems to be very high, people are interested in short terms relationships and tricking (having casual sex) too. I mean that's kind of the point of Grindr, which was founded in the US. My understanding is that gay men in Singapore are more likely to be in LTRs in their mid-20s (my age), than around here.
The specifics of what you are talking about, dating and relationships as a teenager, I know nothing about at all. At 17, I was nowhere near comfortable with my sexuality at all; it wasn't until 22 that I did anything physical with a guy, or 24 that I got in a relationship. So you're already way ahead of the curve. Do 17 year olds of any sexual orientation go to proper restaurants on a date anyway?
At that age, it's probably not the norm to get driven around? Or picked up at one's house?
I have mostly met gay people online. In college there are LGBT gatherings, so that's another way to meet people. Asian universities probably don't have those.