I don't think you can over-cuddle or over-love a child!
The only issue I see here is her interrupting you or being jealous when your attention is elsewhere. My SD was like this, she did not play alone, always had to have someone with her to play, got jealous if her mom or dad had their attention elsewhere. She did grow out if it, especially because they would tell her that they were having "grownup time" and to "go play." Then they would set her up with something to do and leave her to play.
It's hard when your child is an only child and is very social. I think your child is JUST FINE, she is social, she likes company, she is warm and loving.
Just put down some ground rules when you are conversing with adults. Let her know it's not okay to interrupt, and that you need Grownup Time too.
I also agree that at home you can set her up with something to do, play with her for 5-10 minutes, then teach her how to play alone. You might have to give her instructions on what to do.
We sometimes think that everything comes naturally to kids. It doesn't always! With my SD she needed projects to do, or directions. Playing alone can be boring or lonely. My SD did well with craft projects. I would show her how to do it, then she would try, then I'd leave her alone to create.
They have wonderful easy craft projects for 4-year olds!
Good luck!