I have been testing 4dp5dt and it has been a negative. Today is day 5 and still negative. I made a mistake of joining a group on face book which tells me which days people had transfers and got there postive pregnancy test. A lot have got in on day 4/5. I wish I never joined the group because now I feel so depressed today ( I've done 3 pregnancy test today). I transferred two embryo one average quality and one early blast, so don't know if that makes a difference.