I agree that the first thing you should do is eat breakfast! You sound exactly like me a few years ago. I actually had a friend say to me "Why are you so big? You hardly eat anything!" (Nice friend, huh?)
Basically, I skipped breakfast every day growing up. It actually made me kind of sick when I did eat it, because my body wasn't used to it. I might have had lunch, but by mid-afternoon I was starving. I would take a couple of hours to cook something carb-y, because when you get to that state of hunger your body craves fast energy and that was what I would crave. Pasta, lots of fats and sugars... I would overeat, because I was starving. A few hours later my blood sugar would drop and I'd eat again, but in my mind I definitely was not eating that much volume-wise. It was a two-part problem, with my being unaware of what I was eating and slowing my metabolism down by my habits.
So, for this week I'd add in breakfast in the form of something that will keep you full for awhile. Oatmeal, whole grains, yogurt with fruit, and lean protein. Try to avoid white carbs that early, because they can cause all kinds of blood sugar spikes and lows, and you want to start your body thinking that you're going to have an even amount of fuel all day.
I also agree with keeping a journal. Just try keeping track for the first week and really becoming aware of which choices are healthy and which are not. Try to add in more protein, fruits and vegetables if you can and things that will keep you full. Eat 5 small meals instead of one or two large ones.
Move a bit more than usual, even if it's just a 5 minute walk around the house or jog up and down the stairs. Not only will this help you physically, but
mentally it'll put you into an acting mindset and make you feel like you're on the right track.
Also, you might want to see your doctor. I personally recommend WW (the CORE program rocks!) because it worked for me, but your doctor might help you find the right diet in a healthy way, and also will be able to help you gauge progress and rule out any physical problems like thyroid issues, etc.
Good luck! Once you get started, everything else should fall into place.