I did, 4 days after my 18th birthday.
To be honest I look back now and see that I went into some kind of shock. I knew I didn't love my DS initially but I felt guilty for not loving him so I watched other mums and tried to imitate them - how they cuddled and interacted with their babies but I know I must have been pretty bad at it.... I was lucky DS was an amazingly easy baby, he basically slept for the first six months, never cried and was good natured and happy to be put down. If he had been challenging (like my second 13 years later), I doubt I would have coped at all to be honest.
I felt very lonely some days, rather disconnected from the world. Some days I felt flat and remote. Some days were good though, and I was happy enough.
I took care of the basics, fed, clothed, cleaned and held him and in the end the love came, but it was almost a year before it did.
My mother wasn't a huge help, she was and is wrapped up in herself, and my father lived far away. DSs dad left the day he found out I was pregnant. I had friends, but teen friends without children so they were doing their thing.
I think if I had the pressure of social media and 'Insta-Mums', that would not have helped at all. I already felt like a failure so I am thankful that came just a few years later.
Now my DS is 21, confident, funny articulate and getting on in the world. We are close. I am proud of him and me for getting through. It was daunting though initially.