Losing weight while pregnant!

I’ve gained 10 pounds in a month 😑 and I’m only 13 weeks today. So I’ve started eating much healthier, definitely no sugar or greasy fried foods. I called my obgyn to see if it’s ok for me to go to the gym, and they said yes but didn’t give me any details on what to do and what I can’t do... I’ve heard lifting weights is bad, then I heard as long as they aren’t too heavy it’s ok..sooo any suggestions?