But what if I am sending from my exchanges wallet to mine? How do I reduce fees in that case? If the fee is very low how do i calculate the time it would take to go through(will there be a chance that it will never go through)
the exchanges are not wallets.
and the fees they take from you are not bitcoin transaction fees even if it is called liked that.
these fees are the cost of them giving you the services they are offering. you can call it cost of using their platform. if you check your real transactions in a block explorer you can see the fee that your transaction includes is very different from what you paid the exchange.