Early Pregnancy Symptoms-I'm just so scared!!!?

Hello there, my hubby and I found out I was pregnant with my first baby a few days ago. I'm only 4 and a half weeks and so it's still very early days. I have been having intermittent period-like cramps although these seem to be reducing now. I'm also have lower back pain, swollen , tummy and occasional queeziness! I just feel like I could come on any minute! I'm just so, so, so terrified that something will happen to the pregnancy. I keep my fingers crossed every time I go to the loo and I worry at every bit of discharge (just had a bit of pale yellowy discharge). Does anyone else feel the same? Any tips on how to cope with the fear at this early stage? Any advice is much welcome x