I 'fell' pregnant with my eldest at 19. My BF (now DH) was a few years older and although we did talk about a termination, we didn't want that. We stuck together and had the baby.
It was hard, but I was quite mature and not into the drinking/clubbing anyway so didn't miss out on anything that way. We bought a house, got into a lot of debt, had ups and downs, got married, cleared our debts, had another baby.
This is my 3rd pregnancy and due to circumstances with DS2's birth, I was advised to have a termination by my first consultant. I didn't want it, and there are threads and posts by me that show that. It was thje hardest decision of my life, and the fact that I could die and leave my two kids motherless made it no easier.
I had doubts, I knew it woudl regret it my whole life and when I went to the appointment I broke down. Luckily, I got a second opinion that day.
I have supported friends through terminations when they have been the right choice for them. For me, it was not. All I can advise you is that you have to make the choice for you.
Look at your life, how would you feel as a single parent, worst case is that you ex would want nothing to do with the baby/child, he won't pay maintanance. What would you do? Live with your parents or get a place of your own? Would your family support you, give you a break? Imagine all the lives you may lead, basically can you cope with a baby?
Then think about what is right for you. It helps to talk to people, I know what those hormones are like, it is hard to decide with all those hormones racing through your body. I made lists of pros and cons. Tried to imagine if someone walked in right now with a baby and said 'it's your baby, do you want it? I can take it and give it to someone else.' Ignore the pregnancy part of it and think of the baby and you alone at 3am, the toddler you have to take out shopping with you, the 4 yr old with a tummy bug and a fever....
Make the decision for you, nobody else.