I Am Currently 4 Weeks Pregnant. Today I Went And

I am currently 4 weeks pregnant. Today I went and saw my doctor because i'm on Wellbutrin 75mg, and didn't know if it would effect my baby. She switched me to Zoloft 25mg, but I'm not exactly sure what the best way to safely switch over is. She told me to take Wellbutrin every other day then start on the Zoloft, but with how bad my anxiety is that scares me.