She's probably going through developmental changes... especially if she is approaching 9 months old. This is a common growth spurt time & developmental change. Each "growth spurt"...brings about lots of changes for a baby: they hit milestones, physiologically, cognitively, & physically. It's a lot of change for them too, to adjust too.
Here are some links for you with info.:
http://www.slumbersounds.com/baby-sleep-patterns-info.htm
http://raisingchildren.net.au/articles/concerned_about_yo...
Baby sleep patterns are NOT static. They DO change. Just as we adults don't always sleep at the same time, the same length, the same way all our lives... and we too have times of difficulty sleeping or wakefulness. Same for a baby. But developmentally, they are changing much more than we do.
Your girl is normal and this happens to all babies. Mine included. From birth through toddler-hood...a Mommy/Daddy does not have consistent sleep either... baby/child wake up varying times, yes, it's tiring, but they will grow up so quickly.
It's good you have a sleep and nap routine for her... napping is important. At this age, 2 naps during the day is common... and sleep is good for brain development too.
It seems you tried a lot of things to solve her sleep waking up's. So that's good. But...with babies, sometimes we don't always "know" what the deal is and why they wake.
Main thing is to keep consistent in your pre-nap/sleep routines... keep to the same times for it and the same routine. BUT, understand that babies change and it does cause a hiccup in their sleep patterns. It's a phase.
When my kids went through little bumps in the road with their sleeping ability.. I just kept to the SAME routine and sleep times... eventually it passes, and they went back to their "regular" sleep patterns or abilities.
Sometimes too...as they attain other physical abilities...ie: sitting up, standing, rolling over etc., THIS will wake them, because they don't "know" how to put themselves back down, in a perfect prone sleeping position, and then lull themselves to sleep all by themselves. They will do these activities even in the crib when we THINK they should sleep. This is their way of practicing their skills and it's just a natural impulse. It's how they learn.
If she wants/needs to be fed during the night... (for me) I would get up and feed/nurse my kids. That is me. Some say don't and let them cry. For me, I chose to meet their needs as I am that way. It's up to you... but if the baby is going through a "growth spurt" they naturally get MORE hungry and need to feed more AND yes, more frequently. So feed her. Some babies even "cluster feed." Lots and more often.
You mentioned your baby "still wants to be fed at least once a night..." Well, this is normal. For the first year of life... a baby's PRIMARY source of nutrition is breastmilk/formula. Yes, at this age, they "still" may go through periods of hunger during the night and wake up. There is no "generic" time-line of when they stop being hungry at night or "stop" waking up... every baby is different. My son is close to 24 months old.. and he wakes once a night, still, but by this age he is pretty good about getting himself back to sleep on his own and self-soothes. My daughter on the other hand, didn't sleep through the night until she was about 2 years old. Each child is different. Then, too, even when they are older and DO sleep through the night.. .other "phases" occur and may wake them, ie: having to wake and go to the bathroom, poop in the diaper, pee accidents, night-terrors, night mares, teething, a Parent snoring and it wakes them too, etc.
It's NORMAL. Yes. ALL babies go through changes and transitions. Nothing is static with a baby and their constant changes and development. But consistency is what YOU can do... then in the future, when she gets older, it will instill in her good sleep "habits" and routines. Remember, whenever you change their sleep routine/timing/schedule... it can change them and cause disturbance. If you change her sleep routine...make sure it is something you can stick to. Long term.
If she is teething.. well, it will wake them. THey all have their own threshold about it and the discomfort. But it will pass.
I referred to the book- "Secrets of The Baby Whisperer" by Tracy Hogg. It gave me good tips, which I then used or interpreted as I saw fit. I liked this book.
If your daughter is napping well... I would not try to "take away" any naps. They need naps and it prevents them from getting "over-tired" which at night, can actually make them more difficult to fall asleep. Over tired babies/children are actually more fussy and harder to put down.
If you do give her formula at night, as Pediatrician suggested... then keep in mind that your breasts will adjust to that, and you may get engorged at night since you will not be nursing her if she wakes. Do as you see best. (sorry I don't know if you are nursing or using formula) Either way, do as you see best. Yes, some say decrease feeding them at night... and make them get used to it so they don't wake up. It's up to you. For me, I would get up and nurse my kids... they were hungry and would drink a ton. Especially during growth spurts. I just could not deny my children any feedings if they were truly hungry. That is me. If they are hungry, they are hungry. Imagine going to bed yourself, with your tummy growling and having hunger pains. I've done this myself before, and I wake up dizzy and famished the next morning. It does not make me sleep any better.
Also, they get "separation anxiety" at this age. My son got that way from 6 months old, but it passed. They still want to "see" you and know you are there, even if it is sleep time.
Well sorry for rambling. Just some ideas. Your girl is fine... it should pass.
Take care,
Susan