Why do I feel the need to pick up items being thrown out?

I am a 44 year old woman with 3 kids. 2 of whom are autistic. I am very very stressed out and have OCD. Lately though things are getting worse with anxiety. I am finding myself stressed out about every little thing such as the people at McDonalds not filling up the coke cup to the top with soda. I am also, now getting this compulsion that when I drive by someone's house who may be throwing out furniture at the curb or children's toys to pick it up and bring it home. I think I get a charge out of getting something for nothing. I am also anxious about spending any kind of money that I feel guilty and return something. I can't make decisions. Does anyone know why this is? What is my phoebia. Like I said when I see a garage sale I get nervous that I want to go look and my husband rolls his eyes at me making me even more anxious. Then I have this compulsion to pick up anything that is a good deal or for free. Why is that? I also have a problem that I always look to see if I dropped something. I have a fear that when I leave a room that maybe something feel and I am looking under the desk and such even though I dont' think I dropped anything. I also have trouble throwing out anything. Very very stressful. any one with any advice or can tell me what is wrong with me is much appreciated. Thanks..