Irritable , moody , so stressed , no energy , lack of concentration and focus , low libido poor sleep , always hungry thirsty , ( low serotonin ? )

Start with: screening labs for thyroid and diabetes but it sounds like you would benefit from lifestyle changes such as improved sleep hygiene, nutritionally dense meals, yoga, walking, sunlight, and vitamin supplementation to help balance neurotransmitters. There are pharmaceutical options as well. Please seek evaluation by your health care provider.