Worrying about nothing?! Self diagnosing!

I have very irregular periods.
Some 30 days, some 60, some 45. No system, no routine, no regularity. 
I have always been worried this will make TTC hard, obviously. So downloaded two Apps to track my body and pin point ovulation.
I figure it will help but I do find that being on these forums makes me worried about things I may not need to be worried about. 
We've been TTC one month, this will be our second time.
So already I'm going "please, please! Am I infertile?" Hopeless woman brain!!
Anyways so reading some of these forum chats about weight issues, irregular periods, yada yada yada may just make it worse?
I've always been thin, REALLY struggle to put on weight and I'm under the healthy BMI but I'm a healthy person, eat well and don't get sick often. But then I start reading that being underweight can make it hard to get pregnant so now that's just added another thing for me to worry about and makes me be like "crap I need to put on weight. How do I do that?!"
Do I just chill out and keep doing what I'm doing and ignore all this extra information or does it all really have weight and importance in us getting our little package of joy??