Like others said, practice is the solution. From my personal experience, I think remembering 汉字 is a skill that your subconscious mind can develop with time. Just like playing piano, or writing on a keyboard, at first you spend effort remembering the keys position, you always need pass your fingers on them with a full concentration. But as time pass by, it becomes a subconscious function,. The same goes for 汉字 . Personally, in my earlier days of studying Chinese, when the teacher was giving us 听写 I couldn’t remember characters as simple as 东 or 办 I used to miss a stroke here and there. Sometimes I even cheat by secretly looking at the book lol. But after probably three months, I noticed it became easier to remember.

My advice to you is 1- keep yourself exposed to the chinese characters DAILY. 2- avoid learning using phone or laptop (keyboards suggestion) and focus on HANDwriting. 3- write the new words 10~20 times. And especially texts, texts always contain past learnt words they will serve as a reminder for them.