Time for an expectation readjustment.
An average healthy amount of weight loss is about 1% of your bodyweight per week. For you, that means you should expect to lose around 1.5 lbs per week - which is right on track with your 3 lbs in 13 days.
And no, the first 2 lbs is NOT just water weight. A lot of people do sometimes lose faster at first due to losing some water weight, but some don't.
There's nothing wrong with the rate you're losing at. Giving up now would be silly. You're making progress. Why quit while you're making progress?
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