@Sophia, You go girl! So awesome for your babies that you still co-sleep!
(soy isn't the answer, check out Weston A Price. org for more info, though.)
Yes Mom, this all sounds normal. And before I forget, you might want to make sure he gets some good clean fat at dinner before bed - it will help him with the energy to stay asleep. Avocado is a good choice; coconut oil or butter are good fats too, as long as they are clean sources.
He's going to be tired because he's been waking up to find you 'gone', missing. He's uncomfortable on several levels (mine didn't have eczema, but his teeth were coming in (and nursing through that saved may a sleepless night!) and the occasional nightmare/other night issue (can't remember the term). Being there is really important for him - you've built that trust - and babies are used to having their needs met, and you were meeting his by co-sleeping - awesome for him. Awesome for you too, because you have not only 'done it the way nature intended' but you saved yourself the grief of pushing away that natural baby bond.
He is looking for you because he expects you to be there. You are co-sleeping, it is a matter of trust you have built with him. Simply be within touching distance, or put your hand on his belly while he is sleeping (fall asleep that way) and you will sleep better too, once he can trust again that you are there.
You haven't ruined his sleeping. But you need to look up co-sleeping and possibly Dr. Sears and his recommendations for how to work with terminating it when you are wanting it to stop.
Ideally, you would co-sleep until HE is comfortable going to another bed. You might get a mattress now, put it next to your bed, and say NOTHING about it. You might pretend that it is a camping expedition and build some daytime play around it or you might say, hey, this is YOURS, not with the expectation that he want to move right away (which he won't want, I assure you!) How do you want to make it yours (sheets, blanket, etc. although he probably doesn't like a blanket yet or pillow, probably not until he's almost 4ish.)
You can't make him less dependent on you. You CAN ruin that bond of trust. Others will say 'oh, don't let him rule your life', but really, going with the La Leche League take on this - you opted to do just that when you conceived. From nourishing during pregnancy to really, age seven, they are looking to you to fill their needs unconditionally, not just for unconditional love.
Mainstream thinking will have you worried about 'letting the baby rule' and other goofy co-sleeping/bed-sharing myths. And they are myths, and using them as reasons for curtailing that position of trust is only detrimental for you two.
Lack of sleep is just that - but it isn't forever.
Look at a piece of string - add an inch for every year your baby is expected to live. Color in the years your baby is absolutely dependent on you - and you will see this is not only NOT forever, but not very long at all. On the other end of sleep deprivation, it can make you make decisions that cost you closeness in your relationship.
So so much I would urge you to not only keep the close co-sleeping arrangement, but continue it - with the infant on one side, baby on the other - toddler between you and husband if that is your arrangement. Get a side car for the infant if you worry about having room or anything else.
That way you can nurse your infant on demand (good for him and your milk supply and for you - so you don't have to get out of bed!) and also be the comfort for your son.
You might find your oldest sleeps better once the baby has his cry in the middle of the night. He hears the baby being comforted by you, and in turn, goes back to sleep - auditorially soothed by love and attention given to someone else, almost as good as being able to touch you.
You might, for his health and for teething, consider unweaning him (consult La Leche for guidelines for this if you need to, or KellyMom or Dr. Jack Newman (sp?) so you don't think you're moving backwards but instead are helping him - and you - make it through his teething years).
(you might have the bed down the hall, and just wait until he gets into it on his own - it won't happen all at once, but one parenting couple did it this way, and found their 2 year old simply deciding to sleep in her bed on occasion. They found that the nights she did - THEY missed her.)
So much to co-sleeping that no one ever told me. I wish someone had told me when I was in the position you are in, because I am up at o-dark-thirty answering your question instead of sleeping, and when they wake, they are not only unhappy, but screaming because I am not there. I am tired, but can't sit and look at the ceiling or stare at a game on a cell-phone forever while I am trying to get back to sleep - and a flashlight and note book aren't going to work with the 2 lightest sleepers in the world. And mine would go through the day misbehaving because of the lack of sleep - and just now is starting to recognize he needs a nap in the afternoon sometimes (read that all the time : ) but he has more energy when he has more clean fat included in his meal before bed.
It does get better, but before it does, I'm going to have to conquer this and get this middle-of-the-night-starving-need-a-whole-meal-and-wide-awake-need-to-get-work-done THING out of my life!
Good luck, Hope your son gets the relief he needs until he's ready to wean from your bed,
M.