Lifting in the 1st trimester?

Can I lift while I'm pregnant? I'm 5 weeks today. I haven't lifted or really worked out in a long time bc my fertility specialist said no exercise. I already look 4 months pregnant & im absolutely miserable!! Can I lift to get my legs & arms in better shape? I am so flabby and big already!! I've gained 10 lbs since January when I started clomid... I was 132 at Christmas and I'm 143 today 😢 I'm so excited to have this little nugget but I feel like crap!