Feeling anxious and frustrated

Hello everyone. I'm six weeks pregnant today. Yesterday, I went to the restroom and saw blood on my underwear. Similar to period flow. I went to Kaiser Urgent Care this morning and they did a vaginal ultrasound. Doctor was able to see the sac but no fetus. I was told because it's so early in my pregnancy fetus might not be visible and they are unable to determine if it's a miscarriage or just normal spotting. I was scheduled to go back this coming Thursday for a follow up appointment. I'm very frustrated because I wasn't given an answer and the bleeding hasn't stopped. I feel like I'm on my period. This doesn't seem normal to me. Couldn't an obgyn know if it's a miscarriage immediately? I'm

So worried and feel so helpless and anxious. Has any experienced this? Any advice?