Advice/ help

Glow told me to take a pregnancy test Sunday 4 days before my period. So I took one and it came up negative, my question is has anyone ever tested that early and got a negative but ended up missing their period and got a positive test after that? I'm just curious because i have regular periods and I'm on metformin for diabetes and I normally have sore boobs and sore back by now and I'm not feeling the sore boobs and my back is hurting though I'm just curious I don't want to sound dumb but we have only been ttc for 4 months and we are still very new to ttc. This month we did kinda just go with the flow and not really track anything other then the ovulation discharge and back pain I get for 2 days, thanks