Posible for lymph nodes to be felt even when they're NOT enlarged/cancer? I feel some in armpit, doc felt 1, its about 0.7cm he's not concerned. Lymphoma?

Most likely benign. It is not easy to feel lymph nodes that are not enlarged. In young individuals most enlargements are reactive to infections in the region and rarely due to lymphoma or metastatic cancer. If there are pimples or scratches in your armpit , that may explain it otherwise just observe it for a while and seek help if it rapidly becomes larger.