بسم الله
السلام عليكم
Everyone is different. Very few imo become a complete Hafiz without a teacher. A teacher is essential. Someone you enjoy pleasing and also fear. But it is also not impossible to do it without a teacher providing you are dedicated and committed.
The way we did it, I was only 11, would be to learn a fresh side/sides called sabaq daily which we would recite to our teacher. The next day we would learn another side/sides which we would again recite to our teacher. Then we would revise the previous days side/sides again and recite it to the teacher. We would do this daily upto half a juz. We called this sabaq sipara.
So if you memorised a side a day and half a juz was 14 sides then you would be revising a newly memorised sabaq everyday for 14 days. Anything exceeding half a juz becomes revision. Revision would be a juz daily.
The best way to learn a fresh page would be to learn sentence by sentence. When you go on to learn the second sentence, don't worry, you will have forgotten the first sentence. This is completely normal and don't go back to it yet. When you have completed your target for the day, leave the sabaq. You will not remember anything.
Get up early next morning and revise the new sabaq you learnt the previous day. You will memorise it so quick this time and you will remeber it this time. Then follow the above.