I think it's time your baby has their own room. You're spoiling baby right now by letting them continue to stay in your room. Also, they've become used to you picking them up if they scream. Baby knows "if I yell, mom will come and get me". It's never too young for your child to know how to manipulate you.
We let our son stay in our room until 3 months. He's now 3 years old. We put him on a set bedtime every night and we went through a routine. A bath right before bed, a bottle, and then the crib. My son got used to his schedule and started falling asleep at the same time every night. At first we had issues with him getting up, because my husband insisted on going in there to check on him, my son became so used to that that it became a nightly ritual- and was veryyy hard to break.
If you're tired you can't just let your baby cry it out when you're next to them- you'll drive yourself crazy! It's important that either you keep your child in their own room or with your other children. You're letting baby dictate their schedule to you rather than the other way around. If your baby is in the room with your other kids they're going to see them asleep and realize it's night time. I always noticed with daycares kids fall asleep at the same time!
Your baby is screaming and crying because they know you'll just pick them up again, when they scream and cry they're still waiting for you to come in and cuddle them. When your baby took forever to stop crying it's because they KNEW you'd come back- and you did! You have to continue the "cry out" method, I know it breaks your heart, but it's also telling your baby that the screaming and crying doesn't work anymore.
Good luck! ----also, no cereal in the bottle like a previous poster suggested. The baby can aspirate- you don't want to come into the bedroom and realize your child has choked on a chunk of cereal when they were trying to suck out milk. It doesn't sound like your child is still hungry at all and putting your child to bed with a bottle will also cause "bottle rot" - a tooth deformity. The only reason your child screams AS SOON as you put them down is because they know you'll pick them right back up again, as simple as that!