OK. The volunteering alone is unlikely to result in refusal for a fiance visa (economic ones maybe), but it could be used to bolster a refusal on maintenance grounds. The fact that you didn't supply bank statements from either sponsor is certainly not good, but with the contract and the P60, the ECO may choose to overlook it. IMO, it could go either way, and much depends on the ECO. But it is by no means an automatic refusal, so don't despair yet!