My daughter is 4months and she weight 5kg and bith weight is 3kg and she take special formula for infant with regurgitation is she in normal weight?

Close to normal: Not knowing her height, tough to say if she is exactly right size. Generally we like to see birth weight double by around 4-5 months, so she is close to that. Talk to your doctor about what her percentiles are and do her height and weight match up. Also, kids with reflux are usually just a little bit slower to put on that weight until the reflux settles down, usually between 4-6 months of age.