I masturbate a lot, meaning once or twice a day. Is that a problem?
It can be a problem, depending on the reason why you are masturbating. Take a look at the answer to the question "Is masturbation unacceptable?" It is very easy during your teenage years to develop compulsive behaviors as your brain is rewiring itself for adulthood. Since masturbating gives strong pleasure through orgasm, it is easy to fall into the trap of masturbating simply to get the high from the orgasm. Seeking out sexual pleasure solely for pleasure's sake is called "passion" in the Bible. It is the motivation behind homosexuality (Romans 1:26). But it is also what traps people in pornography and sexual sins. "For this is the will of God: your sanctification, that you abstain from sexual immorality, that each one of you know how to possess himself of his own vessel in sanctification and honor, not in the passion of lust, even as the Gentiles who don't know God" (I Thessalonians 4:3-5). The phrase "passion of lust" refers to pursuing things to get yourself sexually aroused, such as looking at pornography.
There is another answer that I would like you read as well, "Is masturbation a sin when it is not accompanied by pornography or sinful thoughts?"