There's no shortcut to memorising, To test whether you have memorised effectively, play only one hand from the beginning of the piece to the end. If you can get all the notes and musical ideas flowing correctly, your piece is secure in memory. However, if you lose the notes when you play separate hand, that shows you are relying on your muscle memory, the most unreliable type of memory that you can use.
There are many different types of memory you must use together to achiveve the best performance, I will not go through them in detail here since it has been discussed many times before in this forum, just run through a search here.
In order to memorise effectively, you have to get all the right notes first. In my experience, a wrong note during practice will become a huge mess in performance, so it is imperative that you get all the notes right during practice. Since you are in a quite a predicament now, I suggest you follow these procedures. Break up your pieces into sections where if your memory fails during a section, you can continue or restart from a section where you are more secure. Practice each section slowly for a few times, and play them only up to tempo after 5 or 6 times. This method works for me pretty effectively, Hope it helps.