Hullo and well met!
I know this will probably make you want to punch me in the face, but when it comes to dating, you only need to go on to one REALLY good date if it's with the right person (my first-ever real relationship began with a nine-hour first date, and we didn't even have sex - just nine hours of talking, straight). And in the end, even that didn't work out because we were fundamentally incompatible to have a long-term monogamous relationship together.
Check out the Life-Stories and Blogs sections - plenty of people struggle with dating. So you are not alone. Poly may well feel like a joke when you struggle with having A relationship, much less multiple ones. So you are already better off in some ways with having a primary for whom you care deeply.
Is finding someone becoming a mild obsession? If it feeds into your negative self-image, it might be good to take a break from active searching all-together for a while and work on self-image issues instead.
Me: bi female in my twenties