Your question is asking about something which is three or four years into the future. That is entirely the wrong focus for you to be having as an MS1. An inappropriate focus such as that could be either a cause of problems or a symptom of them.
The first thing you need is an objective assessment of how you are doing in your current studies. Do you have actual evidence (test scores, input from faculty) that you are in danger of failing? Or is this, understandably, your internal worry about how you are measuring up against a demanding course and other students who present themselves as superstars? If the objective evidence is that you will pass, just keep on doing what you are and try not to obsess.
If the objective evidence is that you are failing, or are at risk of failing, then you need to take charge of the situation immediately in front of you, and do something pretty quickly to change that. But the first thing for you to remember is that you got to med school in the first place because a significant number of people at your school involved in the admissions process thought you had what it takes to succeed. You should take confidence from that.
You may be able to work out what the problem is yourself. Are you studying enough? Are you studying effectively? What is your learning style and are you applying it in the way that is best for you? Typically it's best to understand and learn the big picture in a subject first, and then work your way down into whatever detail you have time for. Talk to your fellow students about what works for them, and about specifics. Can you join/create a study group?
Talk to your anatomy lecturer/a student adviser/learning adviser asap. Ask them how they think you are doing. If you think you know what your problem is and what the solution is, ask them whether they think you are on the right lines. If you don't know what your problem and the solution are, ask them what they think.
If after all this you are still worried about failing, you could check out what the rules are about remediation/retakes at your school. Schools tend to have different rules, but all will make some provision for getting you back on track. You might find it reassuring to know that others have been in difficulties and that a way forward is provided. If you do end up failing, you will need to talk as soon as you can to all possible relevant advisers/lecturers to sort out a way forward. Head in sand at that stage would be the best way to compound the problem.
Good luck.