Hi Tunz,
Yep, I definitely think about the possibility of not having kids - all the time! It does feel like an impossible dream. But then that's how it feels now. Because it hasn't happened yet. Of course, it may not happen ever. That's true. There's no way of knowing.
I practice this "thought defusing" stuff from ACT (Acceptance and Commitment Therapy) - it's about allowing those unpleasant thoughts and feelings, giving them "space", not trying to push them away, but then also "defusing" them, so you don't get caught up in them and get upset. Maybe you've heard of it? You can google it. Dr Russ Harris, The Happiness Trap, is a simple book on it. I am getting help from a therapist though.
All the girls I know who were doing IVF and gave birth said that they felt SO down and SO ready to give up.
I am wishing you all the luck in the world.