I had similar issues in high school. Learning to date and get to know someone of the other sex literally takes practice; it's not something anyone is born knowing how to do. Some people are shyer than others or have a harder time judging when to "jump in" (like learning to jump rope :-) but it's just a learning situation, like learning math, can be emotionally scary but is doable, like you say, you'll get past it eventually.

You can't really miss out on anything in your life as your life has its own course and may/may not be like other peoples. Deciding you should have been dating/kissing boys is like deciding you should have chosen to go to X school in 7th grade or something; you didn't so it's not part of your particular life.