Are you following EASY? In other words, do you feed him when he wakes up, let him play afterwards, and put him down for a nap when he's tired? This is where consistency would come in, not in the form of a rigid schedule but in the form of a routine. So, even though one day he would take his first nap at 9 AM and the next day at 9:30 or 10 AM, as long as you are following EASY as the routine, you are being consistent.
It sounds as if your lo went through the growth spurts but you weren't able to keep things consistent. Growth spurts, teething, colds/flus and milestones throw things off. They sure keep moms and dads on their toes!! However, you need to try to keep things as consistent as possible, even if your baby is trying not to.
At this age, he going through separation anxiety, which is why he starts to cry the minute you leave the room. You need to make sure that it's a real cry and not a fussing/mantra cry. If it's the real cry, you can go back and reassure him that you're there, that he's only going to sleep, and that you'll be there when he wakes up. At his age you can actually say these things to him as reassurance.
It sounds as if you are overtired as well. You need to get some rest if you'll have the strength to get him back on track. Is there some way someone can come over during the day to help? You can get some sleep that way. Or maybe dh will let you take a nap in the early evening? You need to work on you so that you can then work on the baby.
My recommendation: You need to work on the naps. Watch his cues and, as soon as you see him act tired, take him to his room. Do a wind-down routine and put him down for his nap. If he resists, you will need to do PU/PD to get him to fall asleep. It may take up the entire length of his nap (at which point you both be really tired) but it's important in order to get his routine on track. Feed him, then try to keep him up at least 30 more minutes. Then, back to the bedroom. You'll probably have to do PU/PD again since he's overtired but, I promise, if you stick to it, you will eventually get him to nap on his own. It may take a few days, but you will get it! My ds is proof of this (I can tell you stories!!!).
Also, you need to treat the 4:30 - 6 AM wakings as night wakings. You need to do the same here (again, probably using PU/PD). By the way, is he crying when he wakes up at these times or is he playing?
I HTH as a beginning to getting your ds's routine on track.