Jnine!
What are your reasons for wanting to be 147-155? I'm 5'11" and can't imagine being that weight. It's extremely thin for our height. I concur with what Ruth said--you need to read the book, if you haven't already, and you need to move on to Phase 2. Staying in Phase 1 is not only unhealthy, it actually can lead to weight gain. Check out
this thread in the FAQ for more info on that.
I'm not sure you're doing this, but going back and forth ("yo-yo dieting") in weight is really harmful to your body and your metabolism. When you get older, you may find that you've really damaged your ability to maintain a healthy weight without exorbitant effort. While you may not love being 162, consistently depriving your body of healthy food isn't a good way to take care of that issue, in my opinion.
My sister is quite thin but also found that she gained a little weight when she went on Yaz. She has remained on it but has also been intensively working out (no major change in her eating habits) with cardio kickboxing, aerobic classes at the gym, and strength training. She's looking amazing!
She's lost several inches but her weight has remained the same. Here's how she looks now:
Personally, I'd recommend sticking with a healthy diet that includes whole grains, fruits, vegetables, healthy oils, low/non-fat dairy, and lean protein, and focus more on exercise if you feel that you want your body in a different condition.
If you insist on sticking with South Beach, please read up on it. You should never be in ketosis. You need to move on to Phase 2--use these threads in the FAQ to help you:
Emergency Handbook for Phase 2
What's your P2 Combo?
Phase II Food List
If you plan on sticking with dieting, you need to realize that you are trying to force your body to go somewhere it desperately does not want to go. Regardless of what you were able to do in the past, the hormones in your birth control affected your body. Estrogen has a very deep connection with fat storage and may have made a semi-permanent change in how your body works. Getting to a lower weight is going to be very, very hard work and very, very slow. To do it in a healthy way, you need to be very patient. Personally, if it were me, I'd stick with exercise and measuring inches rather than focusing on the scale, which doesn't tell us too much anyway.