What were we thinking?

I really need to keep up with this better! I can't believe its the end of July already and The Bump will be here in roughly a month. There is so much to do and so little time. Trent has been working ridiculously long hours again and even though I'm supposed to be rotating weekends off, with events at work that hasn't quite happened the way it should. Thus this leaves very little time for us as a family. And its really starting to wear on this mama.
Munchkin turned 5 in June and apparently this brings out the attitude of a 13 year old. He is refusing to listen, talks back like no other and tests us (me mostly) of his limits. With my hormones a'ragin, this doesn't mix well as you can imagine. Plus the mister is so tired by the time he gets home that he just zones out and its just me dealing with a teenager trapped in a munchkin's body. Don't get me wrong, I love this kid with all that I am but there are days when I have been tempted to trade him for a cookie and a stiff drink. I feel like I am yelling at him a lot more and there have been more spankings since timeouts have become useless with him. It stresses me out and the mister just gives me dirty looks after the hundreth time of me saying "please quit this, don't throw that, pick this up" No matter what way I go about it, I get attitude and back talk.
For example: This morning as I was once again on morning duty (mister goes in at 6:30 so its up to me to get him ready for the day which is fine when he's in a good mood. bad mood: its the end of the world and very high levels of stress and I'm pretty sure my neighbors can hear some of our "discussions" thanks to my set of lungs/mom's volume..love ya mom!)
Me: You need to get dressed so you can get ready to go to Aunt C & Uncle M's house! (in a sweet, non agressive voice....almost an hour before we need to be out the door)
Munchkin: Not right away!
Me: I don't want to have to argue with you to get you out the door this morning. It stresses Mommy out and I hate going to work all irritated.
Munchkin: I said not right now!
Me: (in a slightly irritated tone of voice) Please get dressed. Your clothes are right there and it only takes two minutes and you know this. This is  the last time I'm going to tell you otherwise you are going in your jammies.
     *side note: we have followed thru on this before, he was upset for a little while being out in public in his very obvious jammies but seemed to be oblivious within the first few minutes of being in the store....
Munchkin: NO! Not right now I said.
Me: ..........Please don't yell at me, I'm not yelling at you. You have been warned and when I am ready to go, you will be leaving in whatever you are wearing.
Munchkin: continues playing while I start getting things together for my day and getting things ready for him
About 20 mins pass and still no sign of changing. At this point I am very frustrated and it's really starting to show. I ask again if he's going to get dressed and I get a snotty "NO!" back. This leads me to get even angrier and a spanking follows with lots of tears, yelling and door slamming. I walk away. I try to calm down but he just keeps going and throwing a fit. And not doing what is so kindly/simply asked of him.

every.single.morning. we go through this. Is it just my hormones or am I really losing it with this kid? I have been so mad some times that I say things that I don't mean (that wonderful temper coming out in me....thanks again mom.....) In fact, this morning I'm pretty sure I threatened to go on vacation for awhile and not come back. I know I shouldn't have but this mama needs a break and soon! Especially with a new one just a few weeks away, I'm not sure how much more of this  I can handle. Any input any of  you mamas have out there would be great! I have been trying to get the mister to go out without the munchkin but with his time being limited with him as well, it's hard to convince him to leave him at home.
*sigh* what were we thinking with having another one?