Some good advice below, and some useless stuff about the woman who Jackie feels should never have been a mother.
These are completely individual feelings, and you are entitled to them, no matter how jumbled they seem right now. This was unplanned, you are hormonal, and you are quite rightly seeing the pros and cons to this. Just because your boyfriend is excited doesn't mean you have to be - please don't let anyone make you feel guilty. This is YOUR body and your life which will change from this moment on.
You do have choices. You can explore them with objective help from a counselor if you like. It doesn't matter if you love your friends' kids - its not the same. It doesn't matter if they think you would "make a great mother" or even if YOU think you would. That doesn't mean you're ready now or that you ever will be.
It is true that many women don't feel at all connected to a pregnancy in the early stages. You don't feel pregnant, you don't look pregnant, you're just all messed up with emotions.
It's also true that many change their minds when they meet their babies. It's also true that many don't feel that instant connection. Those are all legitimate responses to a massive, life-changing event (physical, emotional, financial, sexual….).
I've counseled thousands of women in my years as a health educator - they've made all kinds of decisions, and some have been happy with those choices and others have not. The ability to deal with the outcome has a lot to do with how much support and education they got throughout their decision-making process. Any of the options are possible for any given woman.
My concern is that you don't have anyone you can share your concerns with. You don't want to bring your boyfriend down, but while it sounds like you're leaning toward continuing the pregnancy, it's also possible you aren't sure. But there's nothing wrong with you not being all gaga about baby clothes and car seats if you are questioning whether you want to spend the rest of your life as a parent.
If your boyfriend cannot come down of his cloud to be where you are, then work to get him there and perhaps to talk to a counselor who doesn't have a vested interest in the outcome. If you aren't even sure you want to be tied to him forever, this could have an added effect. Even if "he's the one", that doesn't mean you agree on every major issue - or the timing of them. So you need to be sure you both can support and listen to each other even if you aren't sure you agree - those matters, and how they are approached, set the stage for a successful marriage too.
Maybe you need help figuring out finances. Maybe you need help deciding whether to continue or not. Every woman who has terminated a pregnancy has debated it in her head. That's okay - it doesn't make you a bad person. Not at all.
There's nothing wrong with you for being unsure. Even those who plan their pregnancies go through doubts and rough patches, so there's nothing odd about your predicament. Please reach out for help beyond Mamapedia, and do it quickly so you don't feel trapped.
Good luck to you.