Welcome Ann!
I started DIYing a few months ago. I have mostly TFA/CAP/LA flavors. I have a couple of FlavourArt bottles and maybe a couple of other "less-popular" brands. I run anywhere from 5-15% flavorings per bottle. I am not disciplined enough to record my attempts in the eJuiceMeUp calculator, but I always write on my label my proportions (in case it's really good and I want to repeat it!)
Start with small batches, and do be aware that it may take the blend some time to "mellow"/"meld"/"steep" before it's any good. I mixed a recipe that another member had shared with me. Peach/Blueberry/Coffee-cake type flavor. It was VERY peachy right after mixing (I'm VERY impatient too!) However, I broke it out today (been at least a month, I think, since I'd mixed it.) The peach is not as powerful, and I finally started catching a bit of the blueberry. I'll certainly mix it again. So, be patient.
Susan covered you with the blogs to read. Hoosier does a great job of explaining the "flavor spectrum". Even though you mixed at 5%, it's possible that's too much for *that* flavoring. Not all manufacturers are the same. You may have three different blueberries, and you can use one at 5%, one at 10%, one at 15%, just to get the same result.
Just be willing to experiment.
