Missed period not pregnant

Hello. I have irregular periods, usually I have 45 to 49 days cycle but now I am on my cycle day 62 and I still did not get my period. I had 2 urine pregnancy tests both negative. I also had blood pregnancy test last week but its also negative. I don't think I'll get my period soon because I'm not getting any symptoms aside when I'm getting tired at work, my lower abdomen and lower back hurts momentarily. Any thought please?