Seems like you're just getting into the wonderful world of mixing. You've tried 2.6% to 5% flavor and keep getting the same results. So that means you need to try something different to get a different result. (Knowing this isn't as easy as it sounds. Trust me I've hit my taste buds against the proverbial taste wall numerous times on a number of occasions before I finally figured out I had to approach it differently.)
So, I'm going to assume that you've tried you PG plain, your VG plain, and a mix of non-flavored at your preferred nicotine level to make sure the taste you're getting in all your batches isn't related to your base components and it all has to do with the flavoring.
I have a number of recipes that range from 0.15% to 35% total flavoring. But my tobacco recipes range from 0.5% to 17%. Note that your lowest flavoring % is almost 5 times higher than mine and my highest is over 3 times higher than your highest. If you were doing dessert type flavors and you had the perfumey chemically taste, and you had already taste tested the vapor of your base components, I would say it is a sure sign of over-flavoring. With tobaccos, though, it could be a sign. (It can also mean you're too low.) As a rough guess I would say the possibility that you are over flavoring is around 75%. (With a 25% chance it is under flavoring.)
You can find a great deal of interactive help on the DIY mixing sub-forum.
DIY E-Liquid
You can also find more recipes than you can mix in 6 months on the DIY recipe sub-forum.
E-Liquid Recipes
As a side note, I find it very rare that a single tobacco flavoring makes a great tasting juice. Mine get rather complicated, but I did start by experimenting with single flavor batches to find what tasted like what and to get an idea of what I could mix with what to get the taste I was looking for.
Hopefully we'll see you posting on the DIY mixing sub with your successes soon.
