Aw you should be happy to have thick lips. So many beauty products are designed to give the illusion of full lips. I'm sure you don't look ridiculous! I have pretty full lips too but I still use mac plushglass--to make them look even fuller! I really love a color called Fulfilled. It's peachy-pink. I love it because it brightens my lips but doesn't have lots of shimmer/glitter like other glosses. If you want to downplay your lips or go for a more subtle lip, I would suggest staying away from glosses that have lots of "chunky" glitter. Instead go for something that has a more subtle sheen. Mac will have lots of options!

I have really pigmented lips too. Sometimes I'll go over my lips lightly with my foundation or a light concealer. That way, light colored lipsticks show up better for me--especially pinks. I just make sure to moisturize my lips first and I use a foundation that has moisturizer in it, so that my lips don't dry out.