Open Question: working out but gaining weight?

I (17 yr old, 6'1" male) started working out, weightlifting and eating healthy almost 3 months ago, but I recently started gaining weight. Before I started working out, I was 216lbs. On saturday, I was 184lbs, and now I am 187lbs. I don't look any more lean or muscular than on saturday but I gained 4 lbs. wtf?