My fitness is ruined I can't lose weight no matter what I try, I feel like a fat failure and a loser help!?

Please if you're going to make a stupid comment save it. Semi-professional help if you can give it? So when I was 18 5'11 I weighed aprox. 235lbs with blood pressure ranging to 165/110. I hired a trainer and lost 20lbs because of what my doctor told me. My training sessions were up and decided to take what I learned and try myself. I ate lower calories then usual and lost about 15 more pounds in 2008 in 2009-2010 I stayed at the same weight no matter what I tried, so I went from low calorie foods and increased cardio so I would burn about 900-1,200 calories a day on the tredmill and elliptical. I then lost 10 pounds in 2 weeks and kept it steady for a year in 2011. Yet again I wanted to get to 175 but the same high cardio low calorie wasn't working anymore no matter what I did even regular reps weren't building much muscle. So my friend told me about the low carb diet and muscle confusion where he suggested I take the highest number of weight with lower reps and work my way up to highest number of reps with lower the weight, which when completed I had never seen such results from a diet and the muscle confusion I also did less cardio. I then shedded 25 pounds in 4-5 months in 2012. I was extremely pleased with the results. Then I kept it steady for the rest of the year until I gained back the weight in December of 2012 when I went on vacation until I hit 205pounds which is current! I tried high cardio with low carb for 2 weeks with eating Salmon brown rice and lot of meat-less products containing soy and vegetable, which taste great!, and didn't lose a pound I'm so frustrated I want to cry! I feel like I did all that hard work for nothing I now I'm back to my fat self! I've tried low calorie and low fat nothing is working! I went to the doctors they did blood tests and didn't find anything wrong. He wanted to prescribe me Orlistat but I don't think I want the risks so I told him I'll think about it. Can anyone explain to me what I'm doing wrong? I'm impatient but geezus this is making me depressed I feel like a loser and I'll never amount to anything. I was happy when I had lost all the weight now I don't even want to hit the gym because all the time I put in their is meaningless. Any diet plan or routine would be great or just plain help? p.s. I cannot take supplements with caffeine because of an increase in panic attacks if I do, I cannot even drink coffee.