why am I not pregnant? 😢

My fiancé and I have been TTC for a year now with no luck. He and I have been doing everything correctly. I have lost weight, we are eating healthy and working out, I take prenatal vitamins, and I track my cycle and ovulation religiously. We have even seen dr's to make sure all is well. There is no reason for us to not be pregnant already! I just took a test and it was negative. It gets harder and harder to see the NOT PREGNANT everytime. Everyone around me is either pregnant or has several kids already. Idk how much more I can take.