Mum told me that from the age of 1 to 2 I took in nothing but full-strength Ribera and milk (separately). I'm now 63 and it doesn't seem to have done me much lasting damage.
My DS was a rubbish eater. He's now 31, fit and well, and a better eater - not fantastic but definitely eats more than his toddler staples of nuggets and bread.
I also beat myself up, felt like a bad mum etc.
Advice that wasn't true for me:
"He'll eat if he's hungry". Turns out he has the appetite of a bird so rarely got hungry. And actually, he wouldn't eat what he hated even if he was a bit hungry.
"make it fun". Nope. Many hours I spent doing aeroplanes, cutting sandwiches into fun shapes etc, all wasted.
"get him involved". Nope. Not interested, and didn't work.
What would have worked better:
Eat the same as him and eat at the same time
Don't push, stress or fuss or show any emotion
Don't panic and give him fillers because he must be hungry etc. Stand firm.
Have some clear boundaries (lots of complicated guilt/relationship stuff going on that overspilled into my parenting)
One thing that did work:
When he was old enough we had a deal that we stuck to: if he tried something new he got rewarded, even if he didn't like it. Key was to make this safe: just one bite/taste and if he liked it great, if he didn't we left it. ALSO in this if he did like it we emphasised how great it was for his own pleasure to find something new and nice to eat (ie not that he'd pleased us but that there was something in it for him).
My DS is, I strongly suspect, high-functioning autistic and definitely has a very acute sense of taste.
Most importantly BREATHE and don't let it spoil your life with your babies.