Calories??

How many calories should I eat? 15 weeks 3 days. 
First trimester I lost a few lbs n so far only gained back one of those! Thank god tho! Cuz I weighed 148 before pregnancy now 142 I'm inly 5"3 so I'm like not skinny for some reason having trouble putting on weight I eat currently 2000 cals a day but I'm on metformin to control sugar that might be why