My Baby Bump

Has anyone tried the mybabybump app where you can hear your heartbeat and baby  heartbeat? Well I haven't confirmed if I am pregnant or not but I tried it and I heard my heartbeat and when I put it to my stomach I recorded it and heard something else clearly. I would have conceived end of January if I was pregnant. Is it just my ears playing tricks on me? Last month my AF was 8 days late when it came only lasted 2 days and a week later a 1 day bright pink spotting only when I wipe. Pee test negative before spotting happened and I never took another test again. My stomach is growing.  What everyone think?