I would like to share some advice but I don’t know where you exactly stand in regards to your Catholic faith. You say you are in the Church by your own choice, which is great. Does this mean you have read into the Catechism or read a book on mainstream Catholic theology?
I ask this because it is with faith and belief in what Catholic teachings says (which is all explained in detail in the Catechism), and belief in the Sacraments, that should keep you firmly held in the Church. Because I firmly believe in the teachings of the Catholic Church, I wouldn’t ever consider joining any other denomination, no matter how boring the mass at my local parish would get. Granted, I too have attended a few parishes where I walk out uninspired. But that shouldn’t be a reason for leaving the Church. Perhaps you would feel more comfortable in a different parish with an atmosphere better suited for you? (as long as it’s a faithful orthodox parish that adheres to Church teachings).
Also, it sounds to me that you are spiritually unsatsified by the Church. Have you heard of the Liturgy of the Hours? In case you haven’t, this is the other form of official liturgical service besides the Mass, which all baptized persons have a right to take part in. Although it is meant to be prayed in a group, preferably at a church, you can pray it anywhere you wish individually. The idea is that through this prayer you sanctify the major hours of the day in union with Christ and his Church as other people will be praying with you at the same hour from afar.
In short, I used to be a Catholic who only knew the Mass, and was left spiritually “hungry” for more. My life changed completely when I discovered the Church’s official prayer in the Liturgy of the Hours (LOTH).
I suggest you pick up the 1-volume version of the LOTH, called “Christian Prayer” (the full LOTH is in 4 volumes). I guarantee you that your spirtual life will change and become richer. If you do decide to try praying the Church’s offical prayer, you might ultimately discover that you are being called to start your own prayer group at your own parish (which is what parishes need in these days, to get more people discovering and praying the LOTH). As clichee-ish as it may sound, the Lord does work in mysterious ways, and perhaps he is giving you this “spirtual emptiness” to get you to search for more within his church and thus draw you closer to Him.
You can get Christian Prayer here:
amazon.com/Christian-Prayer-Catholic-Book-Publishing/dp/0899424066/ref=pd_bbs_sr_1?ie=UTF8&s=books&qid=1228699050&sr=8-1