So nervous!

So this may be kind of long and anyone who reads through it is a doll. Last August I fell pregnant with twins and a few days after my missed period the test was very faint. I miscarried at 6 weeks and never once was able to hear their heartbeats.. I found out I am pregnant again a few days ago. I tested 3 days BEFORE my missed period as I just had a feeling and the lines were so there so quick I thought I was looking at the test upside down! I have frequent headaches and just some mild cramping but oh god the gas! My boobs are not very sore and I have not felt that sick really? I’m a little over 4 weeks now but so so scared of a second miscarriage.. I’m 21 and this is my second pregnancy and I’m just freaking out that I’m gonna lose this one as well..