at the time of 2nd test my girlfriend was on PRIMOLUT

Hi,
Welcome to ehealthforum,
Pregnancy does not result if there is no vaginal intercourse or if there is no contact of semen or pre-cum with vagina. If semen pre-cum has come in contact with vagina during sexual contact, chances of pregnancy are possible (especially if the girl is during her fertile days/close to her ovulation time). Urine pregnancy test kits usually start giving positive results (if pregnant) about 20days post-conception (corresponding to about 7 days after missed/altered periods). If she is on hormonal pills for induction of period or prevention of pregnancy, she should get withdrawal bleeding within about 10 days of taking her last pill dosage (if she is not pregnant). Wait and watch for her periods/withdrawal bleeding. Look out for development of any new symptoms if pregnancy is suspected. She should visit her gynecologist for further evaluation and assistance if she does not get her periods within 10 days of expected period dates, or gets abnormal bleeding. If pregnancy gets ruled out and if you are not ready for pregnancy, but intend to remain sexually active, you should consider getting her started on suitable regular birth control measures to be protected (after her periods). She should be regular with birth control use as instructed. Avoid having unprotected sexual contact if you are not ready for pregnancy. She should stop the use of hormonal contraceptive if pregnancy is suspected, or if pregnancy gets confirmed.
Take care.