Generally speaking you cannot have a period while pregnant. You can however bleed. Ask her in a few days what the flow is and how long it lasts. If it's normal as her others are, you can assume she's not pregnant. Unless you're trying to get her pregnant, use condoms at all times, from start to finish.
Thanks bebe & coffee for your advise. My gf just told me that her period come. I suppose this means that she can't be pregnant. Do you think that it is better to test again when her period finish?
If you had sex on June 11 and you tested on 25 June is on the early side of testing. Sperm can live inside of a women for up to 7 days. If you gf cycle is irregular it is going to be more difficult to know when she is ovulating. your gf needs to have had an egg there to fertilize and since sperm can live for up to 7 days you are testing too early to be completely accurate. You want to wait a minimum of 2 weeks after you had sex, but really sometimes that is too early. It also depends on what kindof pregnancy test you are using, some are more sensitive then others, if you are testing so early you want to make sure you are using one that is designed to be used to test prior to your period. The most sensitive would be to get a blood test by your Dr. Good Luck
have her make an appt. with the gyno