Why cant I just make a conversation interesting?

I find that it helps to find people that share the same interest as you. Like if you enjoy reading books, see if there are other classmates that share the same interest. 

I wouldn't worry so much about changing who you are to fit in. Be yourself. And love yourself for who you are first of all. Because that's what helps to develop confidence. When you base your worth on what other people think of you, it can cause you to lack confidence. 

There are plenty of people like you in the world. I'm an introvert too. I find it much easier to talk to other introverts or quiet people because they usually don't judge me for being quiet because they are too. :)

If I'm honest, I struggle with some of the same things in conversations.  Here are a few things to think about.

Remember that not many people have super interesting stuff going on, but we all have a lot of the same experiences and so can relate to each other in lots of ways.

Sometimes I think I'm boring and have nothing to say, sometimes conversation flows so well that I leave someone, thinking of all the other things I wanted to tell them, or ask them.  So remember, it's never just your fault if conversation is difficult, it takes two (or more) and maybe the other person has nothing to say.

You can't force it if someone doesn't want to talk.  You can ask a couple of questions, but then you might have to leave it.  If they're quiet, try not to think of it as awkward, relax - like you would with a family member who you don't need to talk to all the time.  Try to focus on them and be ready to listen or be friendly or kind, if people get that vibe from you, I think they often respond to it.

Talking about arguments, fights, that kind of stuff isn't good conversation, neither is being mean about people behind their back, some people love that drama, but well done if you don't look for it.  Don't be afraid of people that you used to be friends with, move on and either forget or forgive.

Mumbling is a fault of mine sometimes too, I just try to slow down a bit and speak more clearly.  Also overthinking, see above. :)

Relax, smile, you'll be fine.  The people who you care about what they think of you, they are worried about what you think of them.

You are a lot better than most people, who think so much of themselves that they won't even listen when others are talking.