[Mandobart]

You need strong fingers. Barre chords are difficult, but IMHO not really necessary for acoustic playing. You don't have to play all 6 strings to play the chord. I can get the point across by playing an E shape slid up one fret by playing only the A, D and G strings. When I quit playing electric guitar I pretty much saw barre chords as unnecessary and focused learning alternate chord inversions instead. I don't want to categorically say "never play barre chords on an acoustic guitar"; I think learning to play them clean is an important tool we all should have. I just never play the F barre as I think the standard first position F sounds better. I also add a C by playing the 3rd fret A string with my ring finger and 3rd fret D string (the F root) with my pinky. You get all the notes of the barre F except for the low F on the E string 1st fret.

Is your guitar set up for you? High action makes barre chords harder than they need to be. It just occured to me that you're not describing the F barre but the standard first position F where you cover just the first fret of the high E and B strings with your index finger, not barring all the way across on the first fret.

Try the real F barre by playing an E chord with your 2nd finger on the G string 1st fret, your 3rd finger on the A string 2nd fret and your pinky on the D string 2nd fret. Now move the works one fret higher. Now make the barre with your index on the 1st fret across the strings.

I keep thinking of just one more thing. How is your left hand position? Your wrist should be straight. If you pull your left elbow up against your body it makes your fingers angle down toward the fretboard - this effectively shortens them. Keep your elbow out away from your side so your fingers are perpendicular to the fretboard. I hold my left hand like a violin - my hand only contacts the neck in two places. The first knuckle of the index finger touches the side of the neck on the high E side. The pad of my thumb contacts the neck on the low E side. No part of the palm should touch the neck. Palming the neck or wrapping the thumb around limits your finger's range of motion.