Confused on due date or possible twins

I took a test almost 3 weeks ago it said not pregnant.. I took a test a week later and it said pregnant +3weeks.. Either the first test was wrong or im having twins that spiked my hormones levels.. Plus this one my boobs are painful all day every day i have acne and nausea and flutters.. My other 4 pregnancies i never felt all this or any symptoms so early!! Any advice??