Please Advise, sign of autism

Is lack of pointing to things..a strong sign of autism? And also nodding or shaking head no? my baby is 19 mos old po..eto Yung mga bagay na napapansin ko and hindi pa rin po siya nakakasunod sa simple instructions like get. Also she is into banging her head everytime na galit siya. Or alam niya na pinagsasabihan siya.