Sorry to ask a lot of questions but you don't give much information in your post, did you test following treatment such as IVF/IUI/ICSI or following a month of ttc naturally? Have you had any bleeding since you did your positive tests on 19th May? Have you spoken to your Consultant or GP about these confusing results?
Sorry you're going through this, usually a negative is a negative but it depends on a lot of factors like which tests did you use, what time of day did you do them, did you check the wee was concentrated enough etc. If you had 2 positives then you'd normally have had bleeding and pain by now if you had had an early miscarriage.
Sorry my post was a bit bear on info wasnt it!!!!
I did 2 cycles of iui in jan and feb had period march 10th then had break for month fro iui but since then ive had no period i had a small amount of brown blood so assumed af was coming but nothing. I then felt rough and had sore boobs etc so just assumed again it was preiod but still nothing so did test
Mon 19th May pm - positive
tues 20th May am - Positive
tues 20th pm - neg
thurs 22nd am - neg
sat 31st am - neg
Definately ring your clinic and ask for a Beta HCG Blood test as this will tell them if there is any HCG present indicating a pregnancy. I definately think after all this time you are more than justified in asking for the blood test, if they won't do it as your GP.
Sorry, just to be clear, you've not had any IUI since your treatment in February so you've been ttc naturally since then ? You've not had any HCG injections at all ? What cycle day was May 19 ? Do you know when you ovulated ?
Were the +ve hpts the same brand as the -ve hpts ? Did the +ve lines come up within the recommended time ie the lines appeared nolonger than around 10 mins (as if appeared after this time then may have been evaporation lines)....and if different brands, then some are more sensitive than others.
If it's a completely natural cycle, with no drugs at all and they were definite +ve results then it's a possibility that "something" happened as in embie tried to implant but didn't stick properly, resulting in a chemical pregnancy.
As Amanda has suggested, perhaps it would be worth getting an HCG blood test done since you've still had no bleeding.