Splitting bath wiring circuit
I am very confused by your diagram. Here is how I would do it. FYI, grounds ignored but implied and always connected to each other and (as appropriate) to switches, devices, metal boxes, etc.

Combined Fan/Light - i.e., two devices in one box


Panel to switch box in the bathroom: 12/2 - Black (hot)/White (neutral)
Switch box:


Attach two black pigtails to the black wire with a wire nut. One goes to each switch.
Switch box to fan/light: 12/3 - Black (switched hot 1), Red (switched hot 2), White (neutral)
Attach all white/neutral wires together with a wire nut - incoming from panel, outgoing to fan/light, fan switch.
Attach black switched hot to one switch. Attach red switched hot to the other switch.

Fan/light box:


Attach fan hot to one switched hot (black or red). Attach light hot the other switched hot (black or red).
Depending on the fan/light design, it may have one neutral wire or it may have two neutrals. However many there are, attach them to the white wire.



Separate Fan/Light - i.e., two devices in separate boxes


Panel to switch box in the bathroom: 12/2 - Black (hot)/White (neutral)
Switch box:


Attach two black pigtails to the black wire with a wire nut. One goes to each switch.
Switch box to fan: 12/2 - Black (switched hot), White (neutral)
Switch box to light: 12/2 - Black (switched hot), White (neutral)
Attach all white/neutral wires together with a wire nut - incoming from panel, outgoing to fan, outgoing to light, fan switch.
Attach each switched hot to one switch.

Fan box:


Attach fan hot to one switched hot and attach neutral to neutral of same cable.

Light box:


Attach light hot to one switched hot and attach neutral to neutral of same cable.