Hcg only 17

Got my first bfp last weds night at 13dpo. It was light but definitely there. I tested like a nut the next morning and the following day and none of the FRER seemed to get darker. They sent me for blood work Friday morning and got my results yesterday that my hcg was only at 17! I've never heard of it being that low! Well, over the weekend I continued to test and my lines got darker! So now I'm not sure whether I should just prepare myself for a miscarriage, or hold on to hope since my tests started getting a lot darker. Went in for blood work again this morning and hopefully will have my results tomorrow. Anyone ever had such a low hcg and go on to have a successful pregnancy? I had a loss at 9 weeks in July and then a chemical in sept. Not sure how much more I can take. Here are my strips all the way until yesterday morning and the FRER is also from Monday morning, two days after my blood work.