Been ttc for a year and NOTHING sad upset and confused 😕

Hello ladies! I'm 21 and my husband is 24. We have been ttc for over a year and nothing has happened. I don't understand. We're both young. Both healthy. Why are we having problems? I'm so tired and hurt from taking tests every month only to see the same thing. If anyone is in the same situation or has any advise or up lifting comments please feel free to respond! I'm really down today.