Gaining weight!!!

I'm 23 weeks. Before I got pregnant I weighed 120. Then I had really bad morning sickness so I went down all the way down to 102. Now I am 126. Doctor said I'm gaining too much weight. But i only eat twice a day with a few snacks during the day. Am I gaining to much weight? Have you any ladies ran into the same problem?  Also work in retail and work about 40 hours a week and I'm on my feet pretty much walking all day!