Ttc in between training deployments

I'm becoming extremely frustrated. My Husband is in a training rotation and we are trying for our 2nd child when he is home. So far no luck. :( he leaves tomorrow and I was hoping for a Bfp this morning but nope. I feel so discouraged. We are both 27 years old and Idk if that's the problem? I'm not sure if I should go see a Dr about it? Honestly, I'm not sure what else to do??