It's difficult for someone who doesn't actually know you and is just going by what you say to accurately analyse what the issue is.
You may be over intense, you may be needy or it may just be that you're going for full on best friendships with people who don't want that. I know, as DisappearingGirl says, there are times when I have not wanted to have a round at each other's house, constantly messaging etc friendship and would pull back.
My best friend moved away and we have days where we may message all day and then 3 months where we don't communicate at all. But when we get back together/start messaging it's as though we've never stopped.
On the other hand, I know people who would say how kind they are, always thinking about others and that they're always there-and I'm sure they believe that they are. The reality is that they make everything about them, and how upset/happy they are, disappear when real help is needed and are pretty rude to anyone they don't have a use for.
Just because you think you're like that doesn't mean that is how other people see you.
just want to mention- my sister told me that I have a angry face and the way I talk seems sarcastic/ impolite / rude/ angry to people. 😂 but to be honest I am just talking normal.
That may be something to look at. If someone has said you sound rude/angry and you think you're being normal then that would be a reason why people pull back. What does she actually mean there?
I mean, I know people who are as you initially describe, very much people pleasers who go out of their way to please and be helpful, and I can't imagine them also being described as sounding like that. You say obviously you speak differently to your sister, which is fair enough, but your sister doesn't sound like she's talking about you speaking to her, and you also say you're "talking normal", so you don't think you talk differently to her.
I think the best thing you can do is find a couple of people you think will be honest to you. It might be someone who pulled back from you a couple of years ago (don't pick a recent one) or someone you know in a different context, who can tell you how you come across.
Ask them separately how you come across to others. If they agree, then you probably have the reason. If they give two totally different ideas, then say you have trouble keeping friends and do they have any idea why. You may find that they feel they can be more honest when you say that.
Or it could be just one of those things. I've had two people in the last five years who I thought I was close friends with who changed to be pretty nasty. Gradually (and having talked to others) I've realised that it's nothing to do with me, it's them, because they've changed to others too.
Doesn't stop them putting "I'm so kind and everyone loves me" memes on Fb though."