S.,
<<hugs>> Not getting enough sleep is the worst. I'm sorry you are having a tough time. I get a red flag when someone says that a baby "should" be able to do something just because of his/her age. Every baby is an individual, just like every adult is. Do you expect to be able to knit or sink a hole in one just because you are 25? Similarly, not every baby has the same needs. Keep in mind that it is totally normal for a baby to be waking up a couple times a night well into the first year. Despite the press you hear, it is NOT normal or desirable for babies to sleep 12 hours at 12 weeks.
1. Nursing - Breastfed babies are especially in need of at least one night feed. As you may know, breastmilk breaks down more fully and more quickly than formula. The "downside" is that baby needs to eat more often. The upside is that baby is not sleeping all night long with a gut full of formula that is literally curdling in their little stomachs.
2. Age - At nine months, babies are starting to get more interested in the world around them. They may simply be too busy to nurse (or bottlefeed) much during the day. As a result, they make up those calories at night, when it's boring anyway. Has he reduced the amount he is nusing during the day? You might make a point of offering to nurse every couple hours during the day and see if this helps.
3. Growth spurt - 6, 9 & 12 months are all really common times of growth spurts. He is nursing more to increase your milk supply because he needs more milk. Refusing nursings at this point will keep your milk supply from increasing, which may lead to premature weaning.
4. Teething - Tylenol before bed should rule out this one. Also, see how he reacts if you press on his gums. Does he bite down or press into it? Teething for sure! If it is teething, I would just nurse the poor baby and get him through the rough time. You also might leave some chewy toys in his crib, though I'm not sure how much help this would really be.
5. Habit - Some babies are ready to sleep longer stretches at night, but simply haven't learned to soothe themself back to sleep. Cry it out is one option, but probably not the best one. When children are in distress, their cortisol (stress hormone) levels rise, and flood their little bodies. Their heart rate accelerates, their breathing gets faster, and their blood pressure rises. There are now studies that suggest permant effects in the brain for children who are often exposed to high cortisol levels. "No Cry Sleep Solution" by Elizabeth Pantley is a book that may help you. It gave us a lot of good ideas on encouraging our one-year-old to sleep more.
Overall, remember that crying is how your son expresses his needs to you. Meeting those needs as quickly and as best you can will help him grow up into a loving, trusting adult. As you know, this super-needy stage does not last long, and within the next year, he will get so independent that you may soon be missing these baby days. Hang tight, everything will work out for you guys.
Best of luck,
S.