unexpected

Just came from my 2nd ultrasound today turns out I'm actually 6 weeks not 8. Really bummed out. The doctor said that babies still developing and wants me to come back in a week to see how he's doing. I was on the depo shot about 4.5 months ago so my doctor wants to make sure this baby isn't a ectopic. I saw a picture of baby and its really tiny. I'm keeping my hopes up and praying but have any of you mamas experienced anything like this especially getting pregnant soon after stopping depo? Also i don't have any symptoms of pregnancy other than tender/swollen breast and constipation. Also I had an abortion about 2.5 years ago and I had every symptom of pregnancy yet with this one nothing. Technically this would be my 2nd pregnancy but I want it to be through full term.