Constant current for phone charging with boost converter?
Try placing a resistive load on the output of the converter that would draw a 1 amp load (about a 5 ohm, 10 watt resistor). This will tell you if it is a phone or converter issue.

If it doesn't output sufficient current under test, check your input supply voltage to make sure it is holding up under load. If this is OK, start checking your wiring and component values.

If the converter checks out under load, then the issue is with your phone. Many phones follow the USB protocols to check the supply's capability. If it fails to communicate with the supply, it will default to a minimum current to protect the supply.