TTC for 4 years no luck

Hey ladies, I've been using this app for along time now and I have been TTC for 4 years with no luck. I follow the dates that it shows, I always update my period calander, I've done different positions, I've tried just to stop thinking about it and have fun, I've changed my diet and ive lost weight .. it feels that's I've tried literally everything... I'm really in need of help cause everytime I test cause I have all the symptoms and its negative it breaks my heart all over again.. does anyone have tips or suggestions that could help a girl out? Would be so grateful! Thank you