Suggest Remedies For Delayed Periods

Hello doctor, i have a missed periods and i had few pregnancy symptoms as well. This is my 12th week and have lower back pain.
However, i have done 3 home pregnancy test which turned out negative. 2 Weeks back i have done a blood test for hcg, again negative. I always had a regular period.
Is it worth checking now by doing a abdominal ultrasound scan.