your question is very important. its importance arises from the point that you want to fullfil your commitment with God. firstly, you have to know that God wants us to worship him in the way he likes not in our own way. this leads us to the question which is better, to worship God in the chrestian or islamic way. we can't perform both, since their basic believes (nowadays) differ.
i recommend the islamic way for the following reasons:
1- chrestianity worships God, his Son jesus, and the holy spirit. in other words, they believe in more than one God. this contradicts with any rational logic, because if you look in every thing around you, the universe, living creatures, environment,etc.. you will deduce that there is only one God for this world.
2- islam is not just prayers, it is a way of life. it regulates your life according to rules defined by God (Allah)
3- islam doesn't deny other religions. as muslims we believe in Moses and Al-Maseah(Jesus) as prophets of Allah. chrestians and jews doesn't believe in anything else but their religions.
4- reverting to islam will erase all your previous sins while preserving your previous good deeds
inother words, when you revert to islam you will get the following (and more):
1- you will be able to worship and thank God in the way he likes. this resolves the problem of your previous commitment to him
2- your life will be better after following the islamic rules. this is not an assumption, but it is a proved fact. if you don't believe ask those who reverted about their lives after and before reverting.
3- you won't be denying other religions, but you can't practice their way of worshiping God. you will be a muslim. being a muslim is a very precious thing that you won't feel until you revert to islam
May Allah show you the correct path and accept all your prayers