5 WEEKS 2 DAYS: HIGH HCG AND GAS

Hi everyone! I found out I was pregnant September 18th. I went to my ultrasound on Tuesday expecting to be 8 weeks(long story) and found out I was measuring to be just 4-5 weeks. There was only one gestation sac showing since it’s still super early. Anyway, they took bloodwork and my HCG was 18,404. This is my first pregnancy. Is this a high number? Is it normal? I heard it may signal twins seeing as they do run on my mom’s side of the family and my sister also had twins. I know it doesn’t exactly determine twins but just curious. I’ve also felt like my food gets stuck in my chest or it’s just trapped gas. I am always constipated and obviously bloated. Any suggestions on what can help? I don’t get my next ultrasound until October 21st.