Is saying, "There is no benefit in treating what I am experiencing through that,"—in the context of a psychological suffering experience and reciting the Quran that did not prevent what is happening—considered disbelief, knowing that the intention was not to deny the reward of the recitation?

Your statement, "There is no benefit in treating my condition through this," is not disbelief (kufr). It means that you did not benefit from the recitation, and it is not a denial of healing through the Quran and supplications (du'a). Indeed, the Healer is Allah, and healing may be delayed for a reason of divine wisdom, or due to a defect in the reciter. As Ibn al-Qayyim explained, healing is achieved when the medicine matches the ailment, when the physician administers it, and when the patient's nature accepts it. Therefore, continue reciting, for a Muslim's recitation upon himself is best, and there is no harm in seeking ruqyah from someone with sound belief. You must also be patient with the affliction while exerting the means for healing, for in patience there is much good, expiation of sins, and elevation of ranks.