What Causes Delay In Menstruation Other Than Pregnancy?

Hey am Usisipho Fuma am 9 weeks late and missed my periods its 2months now and having all the symptoms of being pregnant and I did several home pregnancy test they came negative and I went to the Midwife last month they did a scan nothing was seen they did a pregnancy test and it came back faint pink line and I did it again this passed monday it came back faint pink line am I preg or what?