I am often confused when people ask me this question. I mean, who am I to say if you're Pagan or not? You may find it helpful to read the article What is Paganism. If you recognize yourself in there, you may indeed be Pagan, but then again, maybe not. And if you don't recognize yourself in there, that doesn't mean you're not Pagan either. You aren't automatically Pagan just because you don't like Christianity.
Paganism is often a haven for those who aren't happy with the religion they grew up in but it shouldn't be and it doesn't have to be. If you aren't happy with your particular brand of Christianity, but you still believe in Jesus, then you should first try to find a way to be happy with Him. One problem that many folks have is the apparent difference in the common practices and beliefs between the teachings of a particular Church and the teachings written in the Bible. If this is the case, then there is certainly nothing wrong with following the Bible and ignoring the pulpit.
There are a number of different Pagan and Christian sects that encompass many different beliefs. I suggest you do some research and find out what what appeals to you. Take a look at Gnostic Christianity, which includes the Sophiai- a female deity, as well as God and Jesus and focuses on personal revelation or Essene Christianity, which is very Earth based. Some groups also honor Mary Magdelene, Mary Mother of Jesus and Adam and/or Eve as ancestral deities. Also, there are many syncretic religions that blend Christianity with Pagan beliefs, such as Umbanda and Santeria. There is also a relatively new development called Christo-Paganism.
That all being said, Pagans don't necessarily reject Jesus. Many of us view Jesus as a prophet and some even accept him as divine. In a polytheistic worldview there is room for God the Father and Jesus, even if you don't accept them as your primary deity.
Feel free also to invent your own religion based on what you've learned and what you've decided for yourself. Pagans do it all the time, and there wouldn't be so many different types of Christianity if Christians didn't do it sometimes too.