Try paraphrasing the prompt instead, that might help clarify the bigger picture, (ie. 'It is only love that changes Terry.')
Then you'll have to work out the 'to what extent to you agree' part. Just a heads up, it's risky to completely agree or disagree with a prompt; try and challenge it in a way that hints at a bigger discussion, but is still very much based on the text and the prompt.
So what you've outlined here:
Also , i was intending to approach the question from the point that there is "nothing other than love that changes him".
Im hoping to say that love does indeed have a significant impact on Terry although several other factors and characters also contribute to his development throughout the film
is a bit of a contradiction because you can't begin by saying love is the
only factor, then later claim there are 'other factors.' Try to tie these concepts together and look at how they might be related (eg. it is love that initiates the desire to change, but a variety of other factors [be more specific - apologies for my lack of textual detail on this one] are what actually
change him.)
For the body paragraphs:
1. The feeling of value (and the realisation of his own potential to be somebody), that Edie's love and presence provides him with .
- Her love brings out the good in him that had always existed , but had always been buried (due to being in the constant presence of the Mob and their ability to always justify their wrong doings)
Good, but make some explicit link to the idea of change. This prompt isn't just about the fact that Terry changes, but that
love is the only thing that changes him. Here you seem to be dealing more so with the idea of whether Terry truly does change, or whether Edie merely brought out a different side to his identity - which is an interesting challenge, but not one that is based on the prompt or your contention. You could incorporate these ideas, but think about what this paragraph is suggesting on an idea-level, because at the moment it's contradicting your overall argument:
Contention: Love has a significant effect, but >insert other factors< are more important for >these reasons.<
B.P: Edie's love brings out characteristics within Terry that were always present --> so not really changing him entirely.
I'd recommend unpacking the idea of change in the text as well. Like, what change(s) does Terry experience, and can we truly call his character 'changed' at any given point? How much of his identity has to be altered before we can call his character 'changed' overall?
Again, try and shy away from packing on evidence and just think about what you're arguing, and why.
2. However, his change it not only fuelled by Edie’s affection, but also by his own desire to become something more than a “bum” and the reawakening of his conscience and sense of morality.
> desire seen in the car ride with Charley (“I coulda had class. I coulda been a contender. I coulda been somebody, instead of a bum, which is what I am”)
> moral conscience exposed in his decision to confess to both Edie and Father Barry & also at the hearing. (“Conscience... that stuff can drive you nuts!” - Terry)
This is much better. Can't vouch for the specifics of the examples, but if they make sense to you and you know what points you're going to draw out from them, then great!

3. Father Barry’s determination to provide justice in a long-lasting and morally just form, assisted significantly in Terry’s development as a character.
> Father Barry is determined to expose the truth
“Terry: If I spill, my life ain't worth a nickel.
Father barry: And how much is your soul worth if you don't?”
> Tells Terry to transpose his violent anger (after he finds Charley dead) and use it to expose the truth about Johnny friendly “Father Barry: You'd better get rid of that gun, unless you haven't got the guts, and if you don't, you'd better hang on to it!”
This is verging on 'topic dodge' territory. When you're given a prompt like 'Love changes Terry' (simplifying for clarity's sake,) and you write a paragraph about how someone/ something else changes him instead, this constitutes a 'dodge' whereby you twist the argument into areas that may relate to one key word in the prompt (here: 'change') but don't relate to the
idea behind the prompt ('love, and only love, changes Terry.')
I'm not saying every single component of your contention has to be evident in every paragraph, but try to move beyond the structure of using evidence as a means of structuring your arguments. So rather than looking at the fact that Father Barry was determined, consider focusing instead on the idea of determination being a more powerful and long-lasting fuel than love. This will enable to talk a little about Terry's ambitions and drive as well.
4. Charley’s Death is the final, pivotal event that changes Terry and causes him to expose the mob. Although he has been aware of the injustice that the mob created, he himself had never been a victim of its unjust ways. When they kill Charley, its suddenly hits Terry that the mob did not have any values or mercy, even for one of their own. This causes Terry really question his loyalty and comes to the decision that he must do the right thing, despite the much obeyed
“D&D” code.
This is just summary, and doesn't tell us anything about the idea that love changes Terry. You're exposing a key event that leads to him changing, but you need to make it clear to your reader
what this means on higher level.ie. The confronting realisation of his friend's (?) mortality causes Terry to change.
Therefore, we can conclude >what< about the nature of love as an impetus for change.
Or you could argue the opposite; the more I try and remember this text, the more I forget, lol

Hopefully the structural outlines will be sufficient and other sources can fill in the blanks!
I'd say spend some time sorting out your contentions and sub-arguments, as that seems to be where the trouble lies
