Basically, every string on my guitar is kinda easy to do a full bend on, except for the high e string, where if I bend it as much as I can, it still sounds flat. I was wondering what I should do, whether I should get a new E string, should I lower/raise the action etc. I'd rather not get a new string, because I have to replace it so often, and I'm gonna change the pegs next time I switch strings.
How hard a string is to bend depends on its tension. The only way to make the high E easier to bend is to use a lighter gauge. Raising or lowering the action will do nothing.
If you currently use a .010 try a 0.009. The downside is that it is more likely to snap and won't last as long.
The other option is just keep practicing, and your fingers will get stronger over time.
You did use one phrase which is puzzling, "bend it as much as I can, it still sounds flat." What does this mean? I typically can bend my E string up at least 3 semitones, so I can decide how sharp or flat I want it to be.
The only reason I could think of that could stop you from doing a full bend is improper technique, such as:
- Using your fingers instead of your wrist to bend: Your wrist has a lot more power than your fingers - to bend you should "lock" your fingers on the string, put your thumb over the neck (this will make it easier, but everybody should be able to do it without the thumb) and rotate your wrist.
- Not using enough fingers to bend: The more fingers you have on the string, the stronger the grip and the easier it will be to bend the string.