I can't stop crying....

So I'm 37 weeks pregnant and all of a sudden I went from being so excited and ready to meet my son to super scared and wishing he can stay inside me forever. I'm not sure if I'm ready to be a mom simply because I'm not sure I'll be a great mom. My mom raised me and my two sisters by herself and I must say she is a REALLY strong individual. I aspire to be just like her but I am sooooo scared that I won't be. My boyfriend keeps trying to reassure me that I will be a great mom but I'm scared shitless.