Possible miscarriage?

i should be 8wks today. At 7wks notices small amount of blood in urine. Doctor diagnosed me with a UTI and gave me antibiotics. Ultrasound the same day showed sac, no baby, measured at 4wks. HCG levels that day measured 5wks. Next day, hcg fell slightly. Ultrasound the next day showed sac measured at 4wks, 2 days and hcg levels are now rising.

Today, noticed tiny red spots in my urine that may be tissue. Is it possible, I'm losing a twin but have a pregnancy and not as far along as I think? I left message for my doctor and waiting for a call back.