Not bad man, but I think if you want to take it to the next level you're going to need to really investigate what all these objects you drew
actually look like, not just what they seem to look like. Sure a chair has a seat, back, and legs, but do these all have to be perfect rectangles? A couch is more then a perfectly square back with slightly rounded square cushions. These things all have properties that exceed squares, and squares are really not sufficient to represent them well. Don't be afraid of curves! I quickly snapped out a new chair to try and show you:

It's not great, I rarely do any iso art and this chair doesn't stand up under any close scrutiny, but the point remains. Don't constrain yourself to rectangles, the representations of things you can convincingly create with them is limited, most objects have curves, and complex areas of light and dark.
As for the lamp, I don't do iso, but what I've gathered from one of ndchristie's posts, draw a square first, then draw the 90 degree circle segments within that. After the circle exists, remove the square reference frame.
Also, whoa you got some crazy color situation going on. When making pixel art it's very important that each color is selected manually and purposefully. You have 200+ colors which is impossible to manage, and on some sites like pixeljoint.com they would not consider it pixel art at all. The carpet seems to mostly be the problem, but even ignoring that I suspect you could really consolidate your palette.