Concern about delayed periods. To worry?

Hello, Me and my gf had an unprotected sex on 29th June, 2019. After that, within 48 hours she tooked an Ipill Post taking ipill from the very next day she started suffering from early symptoms like back ache, severe head ache, stomach ache, lower abdomen pain etc. Within one week of taking ipill, she also got heavy bleeding for 2 days. However, as the days passed the pain started getting reduced. After 22 days of u protected sex we gone ahead with pregnancy test and for the first time it was blank, second time we saw one dark line and after 10 min another line came but it was rarely visible, this happened when we dont the test again for the third time. However her period cycle is 23/24 of every month. So today it is 4th August, but the periods have not yet came. It is almost delayed for 10 days. So the question arises is: When shall she expect periods? Are there are symptoms of pregnancy? How can we force periods to come? Or this delay is just because of ipill and nothing to worry?