Sex is a chore???

My husband and I usually have sex maybe once a week but since ttc it seems to be constant. I am having a hard time with this. It's not that I don't love my husband but I just Am not the type of person that can have sex all the time. I feel like this has a lot to do with why we are having a hard time ttc because it is so stressful for me because I feel pressure to have sex during my fertile week. Any advice??