Irregular period from U72. She pregnant?

Hello doctor..... Actually I had unprotected sex only one time with my gf and gave a unwanted 72 pill within 4 hour on 26 February 2017, after giving pill she came on normal periods for 4-5 days on 13 March....but next month in April she had no periods on expected date 13 April or around .....So she used a home kit pregnancy test on 19 April (on her 6 missed day) in morning time but result was negative....and Actully her second mc periods came on 4th May ( after 20 days of expected date 13 april ). After that her 3rd mc periods came on 24 May just 20 days after her 2nd mc periods date....She took a pregnancy test again on 1st June...report was negative again......And then she had her 4th mc periods on 10 june  just after 17 days of 3rd mc date.I really don't want her Pregnancy. What is the reason behind these Irregular periods ? Is she Pregnant ? Please help I am completely worried doctor. Help !