Struggling and looking for help =(

Okay, so here it goes, laying it all out on the table. I've never done this before posting on a website and I'm grasping at straws.

I need help.

I've been trying to do this myself and I'm struggling. Here's my current situation. I will be 27 this month. I am 5'10" and I weigh between 220-230 lbs. The weight varies depending on my eating, the week, how much exercise I get, etc. When I was in high school and into my first few years of college I weighed about 170-180 lbs. I could run a mile in under 6 minutes, I could bench 300 lbs and I had 6.5% bodyfat. Those days are long gone. I moved to finish college and ended up working my way through the rest of college and now I have a desk job working technical support and have for the last four years. Desperate to change things about 15 months ago I started working out again. At the time I weighed around 245 lbs. I poured my heart and soul into the gym 4-5 days a week and by August/September of 2012 I was down to 220 lbs. I had lost around 25 lbs. I could finally fit into jeans I hadn't worn in 4-5 years and I was feeling much better about myself.

Then comes the slump. My schedule at work changed and I was unable to make the hours the gym was open to maintain my workout pattern. Holidays struck and after Christmas and New Years I tipped the scales at 241 lbs again. I was crushed. All my hard work was gone and I was right back to where I started. So I tried my previous approach, having had some success with it. Now I am back around the 225 mark but I feel like I've plateau'd and I need to figure out how to push past this point.

My goal is to weigh 200 lbs again. I don't need to be 180 lbs like I was in my early years of college but I'd settle for 200 to feel good about myself. A little about my build and current condition are as follows. I'm 5'10" so I'm not super tall. My BMI number is 33 and labels me as Obese. My work schedule recently changed which will allow me to work out after I get off work for at least an hour and a half every day M-F for the foreseeable future. I carry a lot of my weight in my shoulders/chest/legs. I am strong and I am fast. I can still move a lot of weight around and depending on the exercise I can max out what my work's on site gym has for dumbbells (75 lbs). I can bench close to 200 lbs. I can run a mile in 6:45. I can run a 5K. But it's not enough, I still can't drop the pounds. My cardio is solid, my lifting is solid, the only thing I keep coming back to that is destroying me is my diet.

This brings me to why I'm writing this. I need help. I think my diet is the issue and I don't know how to go about fixing this. I don't know when I should be eating ideally throughout the day, I don't know how much I should be eating and what's the best things to eat. Right now I eat when I'm hungry and I eat until I'm full. I know I'm overeating but I don't know how to adjust for this. My eating is so erratic as far as when I get meals depending on the day that I think my body is in starvation mode. Maybe I'm wrong, maybe I have no idea what I'm talking about, but that's why I'm here looking for help.

I want to get down below 200 lbs again. My sister's getting married in October and I would love more than anything to look good for her wedding. I'm willing to try anything and everything, I'm an open book. I've just spilled everything out on the table, I've swallowed my pride and I'm asking for help. I have access to a full gym at work 5 days a week. I live alone so any cooking has to be done by myself, no roommates or significant other around to help.

I'm at your mercy.