pcg2 and Student09 gave good answers.
There is not one saint, priest, or faithful person of any kind who has not experienced these “dry” periods. We question things that can be genuinely confusing, and sometimes we even question things that we know to be truth. Our faith must be tested by making sure it survives questioning and “doubt”. You are still a Catholic, and a stronger Catholic than you would have been without those doubtful times. So rejoice! Thank God that He strengthens your faith and brings you right through the bad times.
It is also helpful to read the logical arguments for the faith when you are feeling doubtful, as Student09 said. Scott Hahn, C.S. Lewis and G.K. Chesterton are wonderful apologists who have helped me through rough times exactly like the ones you are describing.
The best advice I can give you is to keep going to the Eucharist. Recieve at mass as often as you can, go to confession when you need to, and pray, pray, pray. When you get one of these dry times, go to adoration. Sit before Jesus in the tabernacle or monstrance, and tell Him how you feel. Talk to Him like you would a best friend, that is why He is with us. Tell Him exactly what doubts or problems you are having, tell Him you trust Him completely, and pray that He will use these hard times to strengthen your faith as a Catholic.
Student09, good post, and I will certainly be praying for you! I came into the Church this past year (Swam the Tiber Easter Vigil 09 ), and I absolutely love the strong faith that is often found in converts. May God bless you in your journey!
Peace and blessings,