Help with my hair!!!!!!!!!!!!!!!!!?????????…

so my hair is relaxed,fine textured and it's like 3in past my shoulders.I think im damaging it because,I blowdry and flat iron my hair once a week,I use no heat protectant.its not that its getting shorter,its that after like 4 days,it gets really dry.the only hair products I use is optimum hair care stay strong shampoo + Conditioner.I use no sprays,creams or anything because I don't wanna weigh my hair down.I wanted to use mane n tail but I think that's more for white hair.any hair product recommendations? don't say salon because they are too expensive! I only go to the salon for relaxing.