sharedjourney home

I had an IUI done on 4/14 and then went into the RE yesterday 4/27. Acording to the nurse they consider 0-2.9 definitely neg, but mine was 3.3 and she told me to come in on Monday 4/30 to see if it has risen. She stated that I could have implanted late and that is why it isn't showing higher numbers. I had cramping on weds & thurs and nothing. On my natural cycles they are 33-35 days so I'm not even due for my menus until mon-wed. I'm very confused. I'm on profestorone right now and she told me to continue to use them until I know for sure. Doe sany of this sound right?