WannaB, I read your journal. I think at this stage nothing can indicate whether you are having a slow growing healthy pregnancy (totally possible), a chemical or an ectopic. Ectopics can show themselves in many ways depending on where it is located anyway but my understanding was that at least to start with, hcg levels grow similarly to a normal pregnancy and pain would normally be a bit further along.
I had a suspected ectopic last May -but then they consider a possible ectopic automatically if they don't see a sac-, and like you, I was full of fear at the idea of getting the shot and not being able to ttc for 3 months. I was 38 then and 3 months, or worse 6 if it doesn't work first time was the equivalent of the same in years!. The consultant did reassure me though that in 50% of cases, especially when hcg levels are low, the ectopic dissolves itself like a normal miscarriage. This is what happened to me, well, that is if it was an ectopic in the first place since they never sow anything anywhere, just the hcg levels that 'proved' I was pg. By the way, in my case, my line on the frer was as dark as the test, and that was at 9dpo and not fmu.
Try not to let your anxieties take over, I know, easy to say, and I really hope your next poas will reassure you