Hi I Did A Clear Blue Test Ditial One After

Hi i did a clear blue test ditial one after getting a positive result back on first response, the clear blue said 3+ witch on the website means 5weeks or more but i am confused because my last period was only the 13thjan thats only just 5weeks ago i did the clear blue at around 6oclock at night could i be farther gone than the date from my last period?