Having a hard time

I'm 27 weeks pregnant and still working full time w/ and 1 hour and 1/2 commute via train and bus. Im like burnt out and was told I can't go on maternity leave until 5/22. This twin pregnancy is just so different for me. My body hurts when I sit at my desk too long and when I walk there's a lot of pressure under my belly. I feel like I'm about to tip over. I think I'm also having like too much Braxton Hicks contractions that won't go away even tho I drink a lot of water. The Dr just tells me all of this is normal and that I'm already measuring at 35 weeks. Ok rant over.