You seem very self aware op and as you have asked for the truth I will give you my view.
As soon as you have a baby you become a different person with a whole new life. Your previous life no longer exists. Pregnancy and childbirth is extremely hard, and childbirth is like no pain you have ever imagined. I would recommend you look into your pain relief options, and do not rule anything out.
A newborn baby will wake you up every 2 hours at least, sometimes for a few minutes and sometimes for 2 hours, every night for many, many months. Consider now how you will cope with sleep deprivation. Do you think your boyfriend will do his fair share even if he is working?
Supportive families are great but sometimes older relatives forget how difficult babies actually are and all those offers of help suddenly dwindle when baby arrives. How would you cope with this?
Forget about having your dream career. Once you have a baby your life becomes about putting them first, and that includes considering your working life. I have a decent job, but over the last 10 years, I've turned down jobs and negotiated with many managers regarding working hours, because of my children. I've left important meetings early because my children need collecting. I've dropped work like a stone when my youngest cut his head open and had to go to hospital. Your life will not be your own. Childcare is generally offered from 8am to 6pm, weekdays only. As you can imagine, this makes it difficult to do certain careers. Are you happy with this?
Think about your close friendships now, and be prepared to lose about 50% of them when your baby is born.
Questions to consider about your relationship. Does your boyfriend work hard or is he a bit workshy/lazy? Does he have a good relationship with his parents? Does he pull his weight at home with chores etc without complaining? How well does he cope with stress, lack of sleep, and general adversity? Does he have a temper or ever fly off the handle?
Despite this post probably sounding very negative, there are some benefits to having children young. If you really want this baby, the sacrifices make it all worth it, they really do.
If there is any doubt in your mind though, it really is okay to not go through with this pregnancy. It's not giving up, or admitting defeat. Don't worry about replying to this post directly, as I can see you've done so with many others, just consider the questions asked here and your options.