Twins cause early symptoms/positive test?

This is my first month on clomid. I felt ovulation pain on both sides this month. I'm 7DPO, I felt a little nauseous/bloating and have had a headache in the evening for the last 2 days. These are symtoms I had when I was pregnant with my last two but usually got them around 6weeks. So could this because I might have conceived twins? Can you test earlier if you think it's twins? Any opinions.