When can my girlfriend test again?

She don't get her periods regularly she's very irregular. She was put on birth control I think November 11 cause she didn't have one for 3 months but I didn't like them for her she didn't like them neither she was really moody they made her bleed cause she missed like 2 pills so she stopped taking them in the middle of the pack the 2nd week. She tested today and it was negative she sent me a screen shot of this period app thingy lol and the green marks the days we had sex. Is there still hope