I used to feel exactly the same way as you (in fact I think you've pretty much encapsulated my feelings perfectly as they were when I was 17) but, I'll try to give you an idea of how things have progressed since then.
I used to think that life was all about being happy - but by "happy" I meant feeling like was on cloud no.9 all the time. Surely if I was "happy", I'd always be elated? If I'm honest, I thought this would come through finding the perfect girl for me. But as I've experienced more and matured more, I've realised a few things:
a.) You change a lot between the ages of 17 and 25, both in your personal feelings, and in your circumstances. Seriously. You may not think it now but in 7/8 years time you will look back and realise what a difference a few years have made.
b.) There is much, so much more to life than the opposite sex (I know you've not mentioned it in your own post, but this was probably the single most important thing to me when I was 17, so I felt the need to mention it). Obviously being in a relationship can be great, but it's only a small part of who you are - and as you mature this will become more and more apparent (you will naturally become more independent, more so than you think)
c.) Your life gets better as you get more control over it. Ok, so you're still at school at the moment. Soon you'll be at Uni, and you'll be much more free than you were before. Once you finish Uni, you'll be a doctor, and this is not only a fascinating and challenging career in itself, but is well respected and makes you feel you're making a positive contribution to society (another factor which will increase in importance as you grow older). As other people start to show more interest in you, so your own esteem will grow
d.) You'll mellow as you mature. At this time, you'll probably feel like I'm being a condescending prick. But I'll tell you how it is. When you're a teenager (in fact 17 years old is probably the worst time), everything is emotionally exaggerated. When you're sad, you're depressed. When you've had a particularly bad day, you're close to suicide. This will change. Continue on and as simply as it's said, you'll just find yourself more content with life.
e.) You'll gain much more "direction" in life, and as your focus shifts towards achieving your goals, you'll be more influenced by those ambitions, and with a strong purpose in life, you'll feel much happier.
At the end of the day, I'd just say push through it - life will get better and you will get happier