Melatonin pregnancy advice please

When I was pregnant my Obgyn gave me the ok to take melatonin during my pregnancy. I only took it 1-2 times per week before work. I work an extremely stressful job as a nurse taking care of kids with tracheostomies and ventilators and when a kid cannot breath I need a rested mind to think. I did a lot of research (or so I thought) and I felt like melatonin was ok because it occurs in the body naturally. I recently came across some research that said you should NOT take it during pregnancy and it has made me worry a bit. My dd is 7 months and doesn't babble dadada yet or roll from back to front. All she does is sit up. Am I just over worrying? I feel guilty now... Did anyone else take melatonin in pregnancy and have perfectly ok babies? Sorry about the paranoid post... I only took 2.5mg...