Will a clinical pregnancy test be able to determine if I've had a miscarriage?

If I am reading your dates correctly - if you were indeed pregnant then it's unlikely that you will test positive for pregnancy at this point. It sounds to me like you had a very early miscarriage - possibly a chemical pregnancy even. If that is the case then your hCG levels probably never made it high enough to still give you a positive read on a HPT.

Had you been 5, 6 weeks pregnant or more then yes - you would still see a positive HPT as by that point - your levels would have reached the high thousands and can take an upwards of 4 weeks to fall back to zero. But being as this appears to be a very early miscarriage - I wouldn't expect to see 2 lines when you go to test again.

ETA: Just read your update. Sounds like a chemical pregnancy to me.

I'm sure if you miscarry, you still have hcg in your system and it will show up on a pregnancy test. Especially if it just happened. Try to relax though, because you are just a few weeks along and it can be uncomfortable. A little bleeding can be normal, but if you are worried it is too much, go the the ER. You won't have to pay any money there, and then you can take the bill to the local health dept. or social svcs office if its within 3 months and apply for medical assistance. They should cover any past bills from the last 3 months.

Try to relax and stay calm. Although, I know that is hard! Good luck to you.

You might be able to go to a clinic in your area for free. These are usually open on the weekdays if you have time to do.

Have you started any new birth control? I know sometimes different brands can cause spotting in between periods.

I believe the clinic may have to do a blood test and sonogram to be sure. I am sorry to hear about what you are going through! I apologize for not having the best answer, but I saw no one else had answered and thought my advice might be better than none?