First of all congratulations on your weight loss so far - 12lbs is brilliant. Keep it up.
Now to your question - I don't know much about Reductil so I may not be speaking entirely accurately, but based on standard dieting of losing weight at 2lb per week, your goals do seem to be a little bit overambitious.
Now as I said, I don't know about Reductil, and it may be worth checking out the thread on Xenical. I know that it works in a different way, but ...
In general terms, it is very common to lose quite a lot of weight in the first few weeks of a weight loss programme, but this is partly due to the large amounts of water weight our bodies build up when we don't eat healthily. It is also common to find it easier to lose weight when we are heavier, and to find that the losses can slow down quite a lot as we get nearer to our goals.
I don't want to discourage you, but if you set yourself easier goals, then you will not lose motivation if you don't reach your target, and if you go over your target, then you can feel really pleased with yourself.
At a 2lb per week loss (that is really considered the maximum healthy weight loss without medical supervision, which of course you have, so it might be possible for you to lose more with the Reductil), you could be at around 240lbs by your birthday, and around 204lbs by your anniversary. Of course it is always possible that you will exceed those estimates and be slimming into the smaller dress sizes earlier
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I hope that this post has not made you feel demoralised in any way - I just want you to have attainable targets so that when you reach them, you can keep up your motivation to continue this healthier way of life. I'm sure that others will comment and there may be plenty of other people out there on Reductil that can give you more specific advice.