Why am i always so tired when i get the recommended hours of sleep which is 7-8 hours?

Sleep needs vary from one person to the next. 7-7.5 hours is often considered the average need in adults, and not many are maximally functional with under 7 hr. However, some entirely healthy and normal people require 9 or even 10 hours. There's a superior book by a highly regarded sleep specialist. Consider reading it. https://www.amazon.com/Why-We-Sleep-Science-Dreams/dp/0141983760/

There is fatigue unrelated to sleep in a variety of medical conditions and work will be needed under the care of your primary care doc.