Here's my backstory.. So my chest voice usually is much stronger than my head voice. I can easily hit a middle C in chest voice and can usually peak at about an A or a Bb above. I want to be able to sing..say a G4 in chest voice, but also be able to sing a G4 in a strong head voice as well at times like when my chest voice is worn out, ya know?. The is problem is is that when I try to build my head voice (which is usually an extremely slow process filled with lots of awkward sounds and vocal fry noises) my chest voice weakens immensely. One day after doing head voice exercises, my chest voice would only go up to about an F3 comfortably and I could only belt to about a D4 but it had no resonance, was not comfortable, and the sound just didn't go anywhere. Very flat, dull, and stale sounding chest voice but yes my head voice was much stronger.
On the other hand when I build my chest voice power, my head voice almost completely vanishes. On days where my chest voice easily hits bright resonant middle C's and goes way up to A's, my head voice will be REALLY thin and is usually really hard to control. Many times, on days when my chest voice is strong, it'll be really difficult to initiate head voice tones. Lots of times I'll just get vocal fry before my vocal cords compress into a thin, wimpy, bratty, annoying sounding head voice.
So with that said, I came here to ask for help and understanding of my problem so I can fix it. I just want my head voice and chest voice to be equally strong and for me to able to use the two voices interchangeably. Please help thanks.