I'm not sure if this is normal or not

I'm really sorry this is so long. My little boy is 8 months old and I love him more than life itself. However, since having him my anxiety has been through the roof. If I see something in the news or read something on Facebook where something bad happens to a kid, my brain automatically starts to think "well what if that was my kid?". It will happen randomly to, days or even weeks after seeing the story. I'm unable to get these horrible images out of my head no matter how hard I try to shift my thoughts to something else. The only way to get through it is to work through the situation in my head if that makes sense. And then after I've done that I have to check on my kid- if I'm at work i text my mom/husband, who ever has him that day and ask for a picture of him. Or if I'm home I have to go look at him...it's the only way I can relax. I'm not able to concentrate on anything else when this happens.
Last night he spent the night with his godmother so my husband and I could have a date night out. I was up until midnight crying because of the horrible thoughts in my head and I couldn't go see him because he wasn't here. Now it's 7:15 in the morning and I've been up since 6:45 waiting on my friend to text me saying he's up so I can go get him. 
Is this just normal motherhood? I've asked my mom and she said to just get over it because every mom worries and I'm only so bad because he's my first.