Upset about doctors appointment!!

Ok so I went to my doctors appointment today. I'm 27 weeks 5 days. I was told at the beginning of my pregnancy that I could only gain 10-15lbs because I'm overweight (size 18). I lost 30lbs just before I got pregnant and its scary for me to put weight back on and I've been struggling emotionally with it. Well I've put on 20lbs and I'm 7 months along. My doc was rushed today I could tell and my appointment was so quick even though I waited in the exam room for 20 mins. She asked me about my weight gain (3lbs since the last appointment). I told her I don't know what I'm doing wrong because it's not like I'm overeating I make sure I eat good food and every now and then I let myself have a sweet or two. I'm on my feet for 10 hours a day working with one year olds (not easy while pregnant I'm sweaty and out of breath 90% of the time). She didn't really go over why she was concerned and didn't say much else. I also asked her about lifting these 20lb children all day (some days I can barely walk from the car to the house I feel so crippled from lifting). She basically dismissed it and said I was fine to lift. This completely goes against everything I've read about the third trimester. I'm terrified of going on bedrest before I give birth! I can't afford it!! Am I wrong to feel a little pushed through?? Like she had no time for me?? I left and cried in the car on my way home.