All great and varied responses here.
The overall thing is, you need to find what approach you feel comfortable with, how you want your baby to feel, and what you want for your child in the long run.
Crying it out has been, in studies, shown to even change the brain chemistry in a child.
The thing is, every child is different. My first-born, was very much like yours. And this is normal. My 2nd child, was the opposite and was much easier to put to bed and he has his sleep phases too. No biggie. But for each child, they have their own temperament and needs and personalities. Granted, once they get to a certain age, a child, out of developmental progression... does start to get more fussy especially at certain ages... and they WILL have times of changing sleep patterns. All normal. But, I would not just chalk it up to them being difficult on purpose or trying to manipulate you. They don't go around, at this age, premeditating their every move. They are JUST a baby.
I did what you are doing, with my eldest child. I allowed her to self-wean, I co-slept with her, I nursed her ON DEMAND, and woke at all hours to help her get back to sleep, she went through "sleep-terrors" and later as a toddler she went through "nightmares." ALL NORMAL DEVELOPMENTAL phases....per their changing cognitive and development. I would wake and help her, rock her, nurse her, provide her with company, to help her go back to sleep. My daughter also did not self-soothe well, and she did not like anything else but "me" to sleep with. So I survived, it's okay... and NO, she is NOT a "needy" dependent child. Quite the contrary, she is a very independent, creative, self-motivated child and bright. So, no matter what, even if you "coddle" them (which seems to be a 'bad' word and bad thing to do with children), a child WILL grow up, will grow out of it, and will succeed and become their own independent selves. Later. In their own time.
YES it is tiring. Yes that is how it is. NO, it will not last forever. Yes, that is how it is... Parents get lack of sleep. This is JUST the beginning. At each age and stage, at each age juncture...their sleep patterns WILL change. So, we have to adjust to THEM too.
No, it's not "back-tracking"... it's just doing what is needed per the given phase at hand. Mommy's all have to flex and change too. It WILL go back to normalcy.
Sure, try and help her self-soothe, give her a lovey, or put on white noise, or cuddle with her etc. Each child is different. See what works. Or not.
All babies "used to sleep so well..." and then they change. LOL. Well, sleep is NOT static with a child. A toddler will change sleep patterns, a 5 year old will, a teen will have sleep changes, an adult, and elderly person ALL will have sleep changes. Great huh? LOL
I know, it's not easy for the Mommy...but well, before you know it, she will be all grown up and will not need you this way anymore... and it will be bittersweet.
Don't worry, she will grow out of it. Each child has their own pacing. Or, the Parent detaches them. That is the choice.
But with either method... it takes time, there are transition problems to adjust to, and learning curves for baby and parent, and patience. None of it is a slam dunk.
Really, just do what you feel is the best for your baby. Don't feel guilty, don't be hard handed, and ALLOW for transgressions/growth changes/age development phases.
She may very well be going through a "growth spurt" too... and is just plain ol' hungry too. Or teething....
Okay, didn't mean to ramble, just some ideas, all the best,
Susan