You can do any of the above, you can also believe in the Book of Mormon, convert, and still remain a Christian (I am still a Christian just a better educated Christian because I follow the council of the Living Prophet).  
 
To be a Member of the Church and receive the full blessings of the Priesthood and the Temple you must be Baptized and Confirmed a Member of the Church of Jesus Christ of Latter-day Saints. You have the God given right though to make that choice or not make that choice. You and only you can decide what you are going to do with the time that Heavenly Father has given you to use on this Earth.  
 
I have heard of a case where a Baptist Minister believes in and preaches from the Book of Mormon but does not accept the Church. Why, I can't really explain to you it is really odd for someone to accept that the Book of Mormon is true that it's author was the Prophet of God and not accept that the Church of Jesus Christ of Latter-day Saints is the one true Church of Christ on the Earth.  
 
Like I said though we are each free to choose, the Spirit can confirm truth to us to let us know that The Book of Mormon is true, that Joseph Smith was a Prophet of God, and that the Church is Christ's true Church, but even when the Spirit confirms that to us we still much choose what we will do with that knowledge.  
 
For me my choice was to be baptized and join Christ's Church. Yes, this decision has angered my father and has put strain on our relationship at times, but as much as I love my mortal father and strive to obey and honor him, I also have to love, obey, and honor my heavenly father who created me and sent his Son to make this world for me as well as to atone for my sins. To me not following what I know is true is an insult to his great love and mercy towards me, but as I said it is a choice that each individual must make.  
 
I would encourage you to study the scriptures, pray, and discuss with your family what you believe. One thing I guarantee is that if they are as Christian they will love and support you even if they do not agree with your decision.

And I'm confused about another subject. The whole 3 kingdoms in heaven my mormon friend told me the lowest your in peace but not with jesus or god. the middle he said your with jesus. and the highest he said your with jesus and god. But in the bible it says when our heavenly father brings New Jerusalem to the re-shaped earth, that we would all dwell with jesus and god?

The revelation given to Joseph Smith about the 3 kingdoms of glory can be found in D&C section 76: 
http://lds.org/scriptures/dc-testament/dc/76?lang=eng 
The description of the celestial kingdom begins at verse 50. Regarding those who inherit the terrestial (middle) kingdom, it states that they shall enjoy the presense of the Son but not of the fullness of the Father. It also says those in the telestial (lower) kingdom receive of the Holy Spirit through te ministration of the terrestial, and the terrestial through the ministration of the celestial. What exactly that all means, I'm not sure. What I do understand is that everyone will receive the greatest amount of glory that they can abide. Those in the terrestial kingdom simply wouldn't be able to endure the presence of the Father, they would be miserable in His presence. Likewise, those in the telestial kindgom would be miserable in the presense of the Son. 
 
Regarding what the Bible says, I'm not sure as to what passages you are referring to. If you could give us specific passages, we could probably shed more light on them. 
 
Lastly, regarding what you should do about baptism, if you are still legallt a minor (under the age of 18), it would be more important for you to honor the wishes of your parents since they still have responsibility for you. You should continue to participate to the extent that your parents allow but I would not seek baptism until you reach 18 or you are able to get your parents' permission. The church holds the commandment to honor your father and mother in high regard. Once you are an adult, then you become responsible for yourself in this matter. Hope that helps.

I'm also confused about this though, no one in my family is mormon does that mean if i do convert and make it to the highest kingdom I wouldnt beable to be with them because there not mormon cause my friend who is mormon that for eternity they will have their spouse and their family. so how would that work in my case?