Can't stop losing weight while pregnant!

Cara • Baby boy due May 30th, 2017!
Since becoming pregnant, I have lost 15 lbs. I am now 14 weeks along, and at first i just figured it was normal because of nausea but it just keeps coming off! I am not over weight, and was at the perfect bmi for my height pre-pregnancy. I wouldnt say I eat a lot, but I eat enough and eat everything I can keep down. I take prenatals, I eat healthy, and I dont exercise (my job at a daycare working with 1 year olds is exercise enough) so I just dont understand why this is happening and I am getting concerned. Has anyone gone through the same thing? Is this normal? Any insight?