Miscarriage?

Today I am 5 weeks and 5 days. All I can think about is miscarrying. Is that normal? I experienced intense back pain yesterday (it hurt but I wasn't in tears). Will you always experience symptoms if you miscarry in the first trimester? Sorry, this is just so unreal for me! We had quite a journey getting pregnant. My first appointment isn't until next Tuesday (the 20th)! Please help! 😔