Hi S.! I totally sympathize with you! My 20 month old just started sleeping through the night when she was 14 months old. I will tell you what eventually worked for us, although, we have a crib that she would sleep in, so our situation is a bit different.
I was an exhausted, grouchy, breast feeding zombie. I was constantly tired and really not enjoying life. I breast feed her, wore her in a sling as a baby, would almost run in every time she cried to immediately tend to her every need and tried co-sleeping out a desperation. I was opposed to cry it out, as it seemed very cruel and I knew how tough it would be for me. My daughter would not co-sleep, well she would move around waking us all up which just made things worse. I read the No Cry Sleep Solution, which offered some helpful tips. The obvious ones are: putting them on a bedtime routine, which we already were doing, but we fine tuned our routine; Making sure they are filled up with food, water and breastmilk during the day. Unfortunately that and all of the other tips in the book did not work for my daughter after being patient for 3 1/2 months of applying all info. It was like my little one just didn't know how to go to sleep, without my breast in her mouth.
Out of complete desperation, I told my husband we would try the Ferber Method for only 1 week. This is where you let the baby cry, go in after 5, then 10, then 15 minutes, until they fall asleep. I would not even attempt to do this until you have the post nasal drip and allergies taken care of. You will also know if they are in the middle of a tooth coming in, also not the time to begin this process. Anyway, here is what happened, when we tried this with a VERY attached, high demand, breast fed baby:
Night 1- cried for 45 minutes at bedtime, woke 4 times, cried 15-25 minutes each
Night 2- cried for 4 minutes at bedtime, woke 2 times cried for 2-10 minutes
Night 3- cried for 20 seconds at bedtime, woke 2 times, cried for less than a minute
Night 4- wimpered as I set her down at bedtime, woke once and cried for less than a minute
Night 5 & beyond- began saying "Night! Night!," as she held her stuffed monkey & may occasionally have a night waking for a few seconds.
I was so opposed to this method! I cannot deny the results though and how fabulous it worked for our child. Some kids take longer, some not as long and some this method simply doesn't work. What really helped was having my husband do most of the settling, something we learned after the first night. I even put a sippy cup of water in her crib and showed her where it was. I fill it up each day, sometimes she uses it, sometimes not. Anyway, the first night was HORRIBLE for me. And I don't recommend doing this with a younger child either. We do not have her cry it out at her naps yet, as she was crying for too long and I wasn't comfortable with that. I wasn't seeing the results like I did at nighttime. I did notice that she is less apt to have a crying meltdown during the day though. I think she realized that crying over everything doesn't work. This did not change her personality or appear to make her feel distrust towards us.
You adjust to what works for you. Consistency is the key though, so once you decide what method you're going to try, stick to it for awhile. You & your husband must be comfortable with whatever method you choose! Best of luck to you! I hope that you can find a solution that works for you and your family. In the end, I hope you get more sleep and that will result in you being a happier mommy!