You'll get there.
Intern year is being a note monkey ...additionally you'll understand how to navigate the hospital system. 99% of this year is just showing up, no one really expects you to know anything. Would do whatever you're doing in med school in terms of reading about different diseases your patient has (wouldnt buy MKSAP this year). It also does help to also start understanding your interests within medicine and reach out to a mentor to get on a research project (this is more important if you're interested in doing something competitive like GI/cards). Finally, if I were to change anything, I would have taken step 3 during this year on a lighter rotation/vacation...thankfully most of this exam is medicine.
PGY2 is better. You get some leadership experience being a clinical senior. Obviously it helps to have solid interns, but you will learn to triage problems, get people ready for discharge ( you will instinctively start doing this as soon as they're admitted), get better at teaching etc. Would keep reading things like uptodate. I'm more of an audio learner, so I would watch/listen to the louisville lecture series (most lectures are really good, some are poor only because of heavy accents/volume issues) on youtube while eating breakfast/working out/etc. Curbsiders is also a great podcast. You also have more time for research during this year (this is important because you start applying for fellowships in July and the match is in Dec) due to less inpatient months. Finally, my program traditionally does not give pgy2s university icu rotations (we don't have an in house fellow at night so it is generally reserved for pgy3s), so I had to speak with my chiefs in order to get one. I would recommend this because I felt that this really got me comfortable doing bedside procedures (alines/cvc/paras) which really helped out during pgy3 year.
PGY3 has been great thus far. I'm currently applying for fellowship so this time of the year is quite hectic. Otherwise, this year is very chill with tons of outpatient and consult blocks (esp if you're going in to something like hospital medicine). I still read uptodate most days or a review article if I can. You will still have some floor inpatient months but these are even less than pgy2 year. Also can carve out time for research if you want.
Bottom line: you will naturally get more comfortable doing things the more you do them. I still have no idea what I'm doing a lot of the time, so you really do have to "fake it until you make it." Show up, try, don't intentionally kill people, and you will be a fantastic resident. Feel free to PM me if you have any further questions.