I'm scared I have a problem 😢

I'm 24 I have a 3 year old daughter it took about a month to get pregnant with her. It was so easy didn't track or anything. This time all I've been doing is trying and trying and idk what to do. Same partner so I know that's not the problem. How long can it take to conceive the second child? When should I be worried and go to the doctor? Do I have a problem since it hasn't happened right away? I'm scared and stressed and I don't know what else to try. Has this happened to anyone else?