Dont know what to do

Ok ladies need your help. My husband and myself have been wanting to get pregnant, however we have not been really trying just kinda not preventing it. Well today is suppose to be day 3 of my menstrual and I have yet to start. See the thing is I get upset when I take a pregnancy test and it comes back negative. My question to you all is when do you think I should take a test? I have not been more and 2 days late ever. My first pregnancy I knew within a week because my body felt different but I cant seem to tell this time because I am actually wanting another baby. What do you all thing?