Weight loss in pregnancy

I just found out I was pregnant Thursday and I have PCOS. I had no idea I was pregnant and could be as far as 12wks along. I go to my OB referral this coming week to find out more but in the last couple of weeks I’ve dropped almost 15lbs. I was wondering how normal this is? I was trying to lose weight before I realized I was pregnant so I was super excited when I started dropping lbs! I’m overweight according to my BMI. I’ve been going for 3 mile walks and eating healthier but my appetite is super super low. Is the weight loss something to be concerned about?