Well, it is wrong. It does damage, particularly to a relationship with any future spouse. You won't hear that from the world. The experts have all convinced themselves that it's a great idea. And many religious authorities have taken their cue from these same experts.
If it's not a habit yet just stop. If it is a habit you need to work to break it, even if it takes some time. Which will involve custody of your eyes and custody of your imagination. Nobody is blaming you or guilting you here, but you do have a choice, and it does matter. Sex was made by God for better than such a counterfeit.
I suspect a good AG pastor would tell you the same thing in a less public setting. And a bad Catholic priest would not. But I think it would be common teaching between AG and Catholic that it is wrong, at least the more old fashioned AG pastor and the more faithful Catholic pastor.
Whether using a sketch or painting or statue or picture or cartoon or your imagination, still a sin.
I'm a bit out of my place in this Pentecostal and Assemblies of God forum so I'll back away now.