My eldest was never breastfed, and she's perfectly fine. DH wasn't breastfed by his mum, and he is one of the healthiest people I know, he's very, very rarely ill. Only time I've known him to be off work "sick" was when he broke his arm- were talking 12 years of not being ill!
I tried to breastfeed my baby, he's 12 weeks old, hand on heart since stopping my life is a lot less stressful, not worrying about him latching, keeping a breast milk supply up or other breastfeeding concerns. It really damaged my mental health to keep trying when it obviously wasn't working. I think it was the constant feeling of inadequacy that did it for me.
What I'd advise is to look into breastfeeding help, the la leche league are wonderful, I think NCT can support, your local children's centre will have a breastfeeding contact who can help. Or even a private lactation consultant.
See if the support makes a difference, if not then you know you did as much as you could but it didn't work, and that's fine.
I'm managing to enjoy life with my little one more now, there's a lot less screaming because he's not hungry but not able to latch for his food, I'm not worried about trying to keep a supply and I'm not chained to the breast pump anymore.
Though be prepared for an initial grieving process if you do stop .
Wishing you all the best