PLease, please don't give up. Please. I've been TTCing for 2.5 years so not quite been through what you have, but please don't.
It might be good for your mental health to ditch the ovulation tests and so on - but don't 'give up' in the sense of using contraception or stopping sex.
Look, I met a woman a few months ago of about 41 and really grumpily took against her. She seemed to have the perfect life - a huge country home, a thriving business, a gorgeous husband, a bonny lad of about 18 months, and she was massively pregnant (I mean, due that week!).
She picked up on something in my face, I think, and we had a chat about baby stuff. It took her TEN YEARS to get pregnant. Ten years! She had wanted to adopt but her husband was ded set against, so as she reached 40 she concluded that she would never be a Mum.
Anyway - she got pregnant with her son, and given that she was 40 and it had taken 10 years, they didn't bother using contraception again - and BAM, pregnant a few months later, and they'll have 2 children under 2.
Never give up. Honestly. GOOD LUCK.