TTC #1 Jitters

Liz
My husband and I are TTC for the first time, and I can't help but worry that things will not work out. We have only been at it for two cycles, but I am constantly worried I will be one of those with fertility issues. 
I am borderline hypothyroid and have low levels of progesterone and Vitamins B and D but I am being treated for all that. Otherwise I'm a healthy 25-year-old. 
Is this feeling normal? How did you overcome this?