Uhh that room sucks :/ Im sorry. Like it will be really hard to put up basstraps which are the most important parts when it comes to acoustic treatment.

U could setup some normal acoustic foam plates but Im afraid it wont do you much good since your room is not so symmetrical.

I'd suggest you try the monitors out without wasting money on acoustic treatment. If you feel you need some then buy but I would recommend not buying any. You should check out some tutorials and advice on acoustic treatment. (im in a hurry and I didnt find the document I was looking for but google is ur friend here.)

To be honest im afraid acoustic treatment wont do much good in your room.

Id get the monitors and try to evaluate how badly the room rings and whats going on in that room.

I guess you just need to deal with it. You could try to put your table in the narrow end of your room to slightly improve the image but I'm afraid you dont have the room.

Just try the monitors out and learn to deal with your room, not much else I can say im sorry :/

Like others I reckon the room would be very difficult to fully correct.

I would recommend getting near field monitors that you have have as close as comfortable to your ears, then don't have it too loud when you do the mix down, that way any reflections will more naturally by minimised.