Is it possible that my ears are too small for double cartilage piercings to look good?

I suppose it is possible when it comes to opinions. But if your anatomy allows for it, then no, not really. It just depends on how you think it looks, and if it suits you personally. If I were you, I would get two magnetic earrings, or the little clip on fake hoops. Put them where you want the piercings, and check it out. Wear them for a few days, and if you like it, then do it. If not, then forget it. If you are low on cash, you could draw two dots on your cartilage, or use little stick on gems or whatever you can find to create the look of piercings. As far as the other piercings you have on your lobe, I don't think it matters. At least not in my opinion. I think they go together well. Plus, you could always take out the lobe piercings; one, two, or all three of them if you wanted the cartilage more. It's all up to you! Hope you figure out what works for you. Good luck :)