I think ya'll might have taken off more time than me, but I'l try to assure you anway. I only took off a year but it was an a non-academic setting, just working a normal job. The job itself sucked but I miss my weekends and paid vacation so bad right now, but I know how it was getting back into the groove.
You'll be fine. You just need to try really hard to find what study method works for you as quickly as possible. Also, after you see how much work it will take, decide what level of effort you want to give. I am for sure not using the same study techniques I was in undergrad. Flash cards worked great for everything then, it would be too time consuming to do now. Try to actively learn, like actually write things out on a whiteboard or write everything down you need to know on a master sheet and write that out five million times. I think the people who do the worst are the ones who just sit on their asses and re-read the same things over and over again without trying to actively remember it. Passive memorization is useless. Many people form study groups and teach the material out loud to each other again and again, verbalizing it keeps commit it to memory.
Don't just sit there and re-read notes again and again. It might have worked in undergrad. Very few people can make it work in medical school (although I have a friend who does this, he literally does no work until three-four days before an exam. He literally has a photographic memory. He just reads everything once..... it's crazy.)
Here, I have included some images to inspire you.
