Could it be a false positive?

Ashley • I'm 26 years old and have a 4 year old son named Keegan, with my husband Todd. We are expecting baby #2 on March 18, 16.
This is a .88 Wal-Mart pregnancy test. I'm only two days late and had sore breast so thought I would give it a try. Then I added up the days from ovulation and it's only been 15 days! Is that to soon to tell?!