Faint line

So I took a test about a week ago and it was a faint line and that was with a dollar store brand. So I went to Wal-Mart and bought the first response and no line came up. With my first pregnancy the first response test came out as an error meaning there was no line at all both areas were blank so I waited like a day and looked at it and both lines were there and that's when I found out I was pregnant with my daughter and I was already 4 months along when I found out. Someone help me Idk what to do about this. Any advice moms out there