im not an expert but try cleaning the place up a little bit.
read this article for a basic rundown on acoustics, theres better articles but i think this one applys to your situation.
http://audio.tutsplus.com/tutorials/recording/a-basic-guide-to-acoustic-treatment/
this is the part you should def read though
"Every room is unique and everything in the space will effect its sound. Wall angles, flooring, windows, doors and of course its overall shape will all dramatically change the way sound is perceived within the room. The first thing to do in any situation is to identify the problem areas in your room and home in on the issues that need to be addressed. It's possible that some things can be rectified before any acoustic treatment is even purchased."
basically you have stuff all over your floor, your walls, your shelfs everywhere and that will be causing mayhem for the sound travelling through your room.
the first thing i would do is take everything that you dont use for recording and put it either in your cupboard, or find a new place for it. because any or all of this stuff could be degrading your recordings to a certain degree.
if you look at the last 2 pictures you have you see you would have a pretty decent sized area to work with if your shelfs where empty and all the stuff was picked up.
i would get rid of the posters on the wall, move your amps, tear down the shelfs completly, move your school bag, everything like that so that the space is completly bare and empty. then start treatment on the room.
google search DIY bass traps and broadband absorption, diffusor panels, or even just type recording studio acoustics, and learn everything you can. a good place to start is always to put bass traps the corners, and a few panels in well chosen places to absorb mid-high frequencys. seems like nearly everybody does these basic ways to improve sound, so you should be safe with that.
theres all kinds of testing tools availble that you can test what the different problems are with your room, with this info you can better combat the actual problems, which could save you alot of time and money. again hit up the forums and google search, it will be your best friend when learning to set up a studio by yourself.
if you want a better sounding room, be prepared to spend alot of time on researching how to do it, and even more time setting it all up. its not an over night solution. ive been reading up on the subject for 2 or 3 years now and i still no very little about it.
oh yeah and plan it out very well before you do anything! even with a plan, people make mistakes so without one, your setting yourself up for failure.
good luck with the room.