2 faint positives and then a negative?

i took a blue dye pregnancy test 19 days after sex (my periods r irregular) and there was a faint blue line deffinately there tho but i didnt notice it till after 10 min. but before i was just looking for big lines.. same thing 21 days after sex.. with blue dye test. but i thought the first was an evaporation line but whats the chance of two? but then today 28 days after sex i took a clearblue digital but it said notpregnant, but i sware i had implantaion bleeding and cramps and the bleeding was only 3 drops or dark red blood.. and iv had sore nipples...