First, you must believe that this is possible (it can be terribly daunting). Quit 'trying everything'. Choose your tack and stick to it. Small reward (or at least a happy 'potty dance') when there's success, and as little as possible notice for 'failure(s)' She IS old enough to use it on her own, but for some mamas, there's almost a desire to 'keep them little', and the effort to help them mature is 'half-hearted'. Obtain the attitude that you're doing this for HER -- enabling her. Think, 'let's do this' instead of 'I'm doing this TO her'.
This idea of 'when they're ready' is OK in today's envirinment where it's easy and possible to just keep buying disposable diapers forever, but it simply wasn't practical 'back in the day' when mamas had to WASH diapers and reuse them. I guess I'm of the 'old school' and feel that I have a right to push them a little to be more self-sufficient instead of catering to their 'readiness', as long as it's done with a happy and positive attitude.
I'm at our daughter's right now with her 18 mo old girl on the potty playing with a shape sorter as we speak. I'm in the next room. I just tell her to stay there until she pees, and she can get up. She gets up some (and I have her to sit back down), but she does eventually pee a little, so I make a big praise over her success, diaper her, and that's it. She'll get it. I love potty training (better than her mommy does! LOL), so I get to 'do the honors' when I'm here.
Don't use the pride or disappointment of others as an incentive. Make this about HER. When she learns to potty every time with no messes, she can choose her own underwear at the store. Start looking at them now, and ask her what ones she'll want to buy (and if you're afraid that they might 'sell out' of them, buy them when she's not with you and hide them). Make sure she's dry and no poopy pants for at least a week before letting her have them. Keep a chart of successes (not failures).
I'm sure you'll get lots of other advice, but this is doable! All my 4 were fully trained by age 2, and only the 2 boys had a few nighttime (wet) accidents after that.