Elaine, have you tried faking a crease? Looking up ideas on the net, via youtube and whatnot? It's certainly a common issue. I mean, for example, if you look at
YouTube - Find and Fake a crease on Asian monolids! it shows a girl creating a crease. Yes, it's super neutral, but you can always translate that into colours. It would certainly take practise, but can absolutely be done. Another is
YouTube - Neutral Defined Fake Crease Tutorial , and she appears to have a bunch of looks up.
You can also simply look into eye carving. I know MissCheivous posted a video on it a while ago (even though I wasn't super fond of the overall result, but hey, I know it exists), and a number of girls who even have creases do it. It's all the same idea, really. Eye 'carving' simply emphasizes and defines the shape for those who have it naturally, or can create it for those who are lacking it.
Even if you find examples in neutrals, you can translate that to colours! I'm really sorry you're so down about this, and I know this stuff is difficult, but it could be worth trying.
Have you tried a lash primer? I have really long lashes, but they're super straight. They don't like to curl. Or stay curled. At all. So, I investigated a bit: I find a lot of people are huge fans of Shisheido's lash primer, say it actually holds a curl, etc. Rave reviews. HOWEVER, it's pricey. Yuck. There's a South Korean brand called Missha that makes a lash primer in a white tube. You can nab it off of ebay for about $10. It has the fibrey stuff to add length to your lashes, and it's supposed to hold a curl pretty damn well too. It makes my lashes stupidly long, to the point that they hit the bottom of my brows if I curl them. Stupidly long. Doesn't really hold a curl super well for me, but it helps some. The other thing is to use a heated lash curler, preferably one designed to be heated, but plenty of people just blast their standard ones with hair dryers to warm them up. The heat, of course, makes your lash take the curling better.
How much of this you're already aware of and/or have tried, I don't know, but that's what I've got for suggestions.