Anemia or normal pregnancy symptoms, out of breath, heart racing, dizzy sometimes, and I'm 16 weeks preggo.?

ok to start off... im 22 years old and im 16 weeks pregnant. this is my 4th pregnancy but i only have one daughter and one child on the way.. ok so to get started, for the past few months {about 2 months or so} I've been experiencing shortness of breath and a racing heartbeat. i only get it when in the mornings or when i walk up the stairs or walk around or do anything strenuous. in my past pregnancies i did have slight anemia but with this one the heart racing, out of breath feeling, dizziness sometimes is just crazy! i dont feel like ping out or anything but when my heart races it doesnt stop for like 5-10 mins sometimes. i went to the ER the other day and they did a cardiogram to see if my heart rythums were fine and they are. i've also read around that in some pregnancies women do get this out of breath feeling and their heart races a bit due to the increase of blood in their bodies. so my question is, are these normal symptoms or pregnancy or does this sound like anemia or something else? those are my only symptoms. thanks for your help!