Don't listen to them.
You will be fine just as thousands of women before and after you will be fine.
I was 24 when I had my first. Engaged, living together, family business... for the first 8 months of pregnancy anyway. I discovered he'd got another woman pregnant and we split up.
I moved back home - over 300 miles away. I was homeless and lived in a mother and baby home for a year because I had no one. I was threatened. My child was threatened. And, in all that, the thing that kept me going was his happy smiling face, his giggles, his security. There were no distractions, no arguments, no one else to consider - just me and him living our lives every day.
I had no friends, having moved so far away, I had no family support - my dad was recently remarried and my mother, well she's another story for another day, but I was completely on my own but the night before he was born (was induced) we were walking round sainsburys picking up some last minute essentials and she turned to me amd said, "I bet you wish you weren't having him kpw, don't you?" I had similar comments from her as you are getting and it just made me more determined than ever to succeed and prove her wrong.
And, yet, I had the most wonderful time. I look back on that time as one of the loveliest times of my life. Just me and my baby pleasing ourselves. Yes, there were hard times but he was never hard. Being his mum was never hard.
I moved out into a flat and we were a team. I went to university as a single parent, when he was 19 months old, and got a first class degree. He went to university in another city with me every day to attend nursery.
23 years on, that baby is a man who has graduated university, works full time and with whom I have a wonderful relationship. He's turned out to be everything I could have hoped for.
There's nothing special about me. I grew up in abuse, I struggled to find myself, I lived with great sadness for many years but none if that was directly related to him.
It's not a disaster. It's an adventure with your tiny human. Someone you will teach and learn from. And you will learn. About your capacity for love, your resilience, your strength.
And it will be the most amazing adventure. And that's what you can tell anyone who dares to try and undermine you.