Talk to Gynecologist on Difficult Getting Pregnant

I am trying to conceive from last 3 months. i used ovulation prediction kit as well for ovulation accuracy. and we tried for all days in my fertile window. I dont know where i am going wrong. maybe my diet is not so good and i was also very stressful. can you tell me some supplements that i can use. my periods are always regular. i am also using flo app and its tells exact ovulation and period expected dates.