Help me out please

I just found out I'm pregnant after trying for almost 2 years. I've been spotting since I found out, minor cramps here and there and a backache. I had a quantitative hcg test done on Sunday evening and my hcg level was 82.1, repeat it tomorrow morning to see if they've gone up by at least 50%. I'm worried I'm having a miscarriage. Anyone else have low hcg levels and gone on to full term?