I have a GF that had a miscarriage and then a little over a month later got pregnant. so it is a possibility. What CD are you on? is it possible to do a HPT yet?
You can get pregnant as soon as you start ovulating after miscarriage. These can be the signs of pregnancy or due to hormonal changes. You can test 1 week- 10 days after you miss your periods or you can test for pregnancy by a highly sensitive pregnancy test 10 days post ovulation with a sensitive ( 20 - 25 mIU ) pregnancy test.. Also I would suggest you to get your serum HCG levels estimated since this is more specific than urine for pregnancy tests. The HCG (it is a hormone) levels rise only in pregnancy and its presence will confirm the status of your pregnancy.
If pregnancy is ruled out, then other causes of delayed periods need to be looked into. So my suggestion would be to consult a gynecologist and get serum HCG levels done.
I hope it helps. It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.