Threatened miscarriage

I don’t know how far along am I because the doctor must’ve got my dates wrong. Due to I missed my period since July. I took pregnancy test last month it was negative until the first week of august and the 14th later. It came back positive.I took many test. It all came positive. It’s my first pregnancy. I had contacted my doctor because I was having light cramp on my left side. No spotting or bleeding. They told me go to ER, when I went they diagnosed threatened miscarriage because they couldn’t find out how far along am I, confirmed pregnancy in urine and blood, my hcg blood was at 293, there’s no signs of miscarriage and ectopic pregnancy… through the ultrasound , there’s no baby in the ultrasound because they think I’m too early, the doctor in ER was not doing her job as she’s doing because she’s was “you can get a false pregnancy “ then why am I getting pregnancy symptoms. Lol before she didn’t believe I was pregnant… when my blood result came back for everything… have anyone went through this ? They told me to come back for my recheck my hcg blood hormones, I hope it increases…. I’ve been stressed and confused with the whole ER situation.