Daughter like mother?

My mom keeps telling me she thinks im pregnant. Why is because when she was pregnant with my older brother she still got her period for the first 4 months. Well for me I have similar symptoms to when she was pregnant with him. My boobs got bigger very fast over about a month or so. Then I have started to gradually put on weight. I havent been able to gain much weight for over 2 years but all of a sudden the last 2 months I've put on weight and I feel bloated all the time as if I just ate the biggest meal of my life. I want to test but whenever my mom tested with my brother it was coming out negative. I dont wanna get my hope's up. But me and my brother are the closest between me and my siblings. Both my brother and I were supposed to be twins but both of our twins passed away while developing.