Am i overreacting?

I've known my current boyfriend for 3 years and have been with him for about 7 months. Before him I was in a really abusive relationship and YES I'M OVER IT. My boyfriend is wonderful to an extent. He spoils me, he's great with my kids, we vent to each other but then there's the downfalls. I am not the type of person where I let the negative things about a person get to me and have tried letting things that bother me, go. However its getting to the point where he just irritates me and I wonder if I'm overreacting.
Here it goes... to start sometimes he will sit down and sigh a bunch until he is asked what's wrong. Its so bad to the point I could be in my back room which is 4 rooms away from my living room and I can hear him sighing, like as if he's purposely doing it so that he's asked what is wrong.
Then, he usually comes to my house so I've only seen his apartment once and it was completely disgusting, cat litter on the floor(with "feces") plates with food on them laying all around. He said once his room mates stopped cleaning up he did too because he was sick of being the only one cleaning. But then when he offered to stay with my son while I worked I came home to a sink full of dishes, overflowing trash and him sitting on the couch playing video games. He said "oh I was meaning to get to that".
There has been times he has blamed things on my kids. For example he left a bag of chips at my house and my girls ended up eating them. I bought another bag for him, when he got to my house my daughter said "mommy got you another bag of chips because I didn't realize they were yours" he turns around and says "in my defense he knew they were mine, pointing to my son"... second time, we're in a hurry so him and my son eat cereal. after getting my toddler ready I notice a bowl of milk sitting in my sink. I don't blame anyone I go into the living room where both him and my son are and I say "hey guys just remember when we're putting dishes in the sink that we rinse them out". when we're out he tells me he gives me this huge story and ends up telling me that my son had to have done it. it was a bowl of milk! why in the world would you make sure you blamed a 9 yr old over a bowl of milk?! I didn't scream at them, I didn't put a specific blame on either of them, what was the point of making sure I knew it was my son?!
Maybe I am wrong but I really do not like that at all. He is the adult.
last thing which I guess it not really a big deal but I feel like its a self worth thing.
If we go out somewhere he only wants to wear sports pants. which I get he wants to be comfortable, but he never wears clothes that actually fit him. his shirts aren't long enough so if he sits down his back and butt are showing. People he knows are always telling him how trashy he dresses and to dress decent but he says no, he will dress how he wants.

Of course this is not the first relationship I've been in so these things don't get to me because I'm not used to having a guy around. Sometimes I feel like im with a child or a lazy person. and yes I know the stereotype is that men are like your children, but really? this bad? no one I know, not even male friends are this bad. I may be overreacting, everyone I know says im not and they wouldn't put up with many things, but they may just be saying this because they know me :-/ the main question here is it normal for him to act like that?