B hcg< 1. 2 but back pain n bloating.

My LMP was 3rd september, one day after the end of my period, on 6th september, I and my fiance rubbed genitals for small duration, there was no penetration and no ejaculation (I am a virgin). On 30th september I got my period ( expected date) but the period was slightly lighter in flow (but had clots and period like appearance) and filled only 4 pads in 2 days ( I always get periods for only 2 days and I have hypothyroidism since 15 years) I googled the cause of this light period and was shocked to find that it can be an early sign of pregnancy. On 7th october morning, I went for 2 urine pregnancy tests which were negative and same day I did beta hcg blood test which also came negative (less than 1.2). But i am experiencing some back pain and abdominal bloating, i dont know whether this is due to stress or is there any chance I may be pregnent? I am really stressed out and getting anxiety, please reply. Thanks you in advance doctors.