Does every mother think about this or do I need help?

I have a six month old daughter who is my entire world. But sometimes I have thoughts of accidentally hurting her or someone else hurting her. I try my best not to think about it but I do. I'm so scared that I may accidentally hurt her. I get overwhelmed with fear that something will happen to her. I know I won't do anything intentional to her but I'm scared I may accidentally drop her or roll over on her in my sleep (yes I bring her into bed with me sometimes). I look at her as being so fragile and I could accidentally hurt her without meaning to. It scares the hell out of me. I wake up like three or four times a night just to make sure she's still breathing while she's sleeping in her crib. It's like I'm obsessed with keeping her safe and unharmed. I know I can't protect her from everything but I still try. I just wish I could stop having thoughts of something bad happening to her. I can't live my life without her, she's my world. Does other mothers think like this or is it just me? Do I need help? Please answer and only mature answers.