I'm also 20 weeks. I've found that eating healthy and exercise really helps me feel great and keeping a journal alleviates stress. My husband is incredibly supportive -- so perhaps ask your husband for massages or to help you with whatever is stressing you out
Sounds like maybe take some things off your plate or spend less time with people who stress you. Hard to say if don't know what the stress is.
I try and do an activity that will take my mind off of it like taking a walk or quilting