I'm worrying myself sick

Okay lady's has anyone else had this experience and it just be nothing? My last cycle was March 14th and according to my doctor I should be 9-10 weeks but I'm only 6-7 weeks. He said I either got pregnant "on time" and the baby died and I'm still carrying (like a missed miscarriage) or everything is okay and I just ovulated late. I have an ultrasound sound Tuesday to see if my pregnancy have progressed but I'm so so nervous. I keep having bleeding and strings of tissues. 😔 I really want this baby my husband and I have tried for 2 years and now I'm finally pregnant I feel like I can't enjoy this.