Q: how do I transfer my music from my ipad to my iphone

Hello Tenderbeetees!
 

From what you've posted, you're wanting to get your same music on the iPad to the iPhone and computer with iTunes.  We can certainly check on things for that. 

If the songs are ones you've purchased from the iTunes Store with your Apple ID, then as long as all your devices have the same Apple ID signed in, you can download them: Download your past purchases - Apple Support

If it's songs with Apple Music, then your Apple Music Library should sync across all devices and then you can stream or download the songs you have saved to it. 

iTunes 12 for Mac: Stream or download unlimited songs with Apple Music

iTunes 12 for Windows: Stream or download unlimited songs with Apple Music

Best wishes!