You have asked a couple of questions - and the best answers will always come from your AO. However, I'll try to provide some points to think about:
1. The report that is generated by the AIM Cadre is not considered an "interview." It will be part of your admission file - but you have to consider that the board will only have that piece of info for the candidates who participated in AIM. Furthermore, the majority of candidates who attended AIM will fall squarely in the middle of the bell-curve on the rating of the report. Only a few AIM participants will get a "highly recommend" rating, and only a very few will get a "do not recommend" rating, the rest will receive a "recommend." The AIM report is more of a tool for the Cadre to learn some lessons in their leadership laboratory than it is meant for a delineator to the admissions board...so I wouldn't be too concerned about the AIM report.
2. An admissions interview is not required for consideration by the Cadet Candidate Review Board. However, if you feel like your file doesn't fully tell your story and you want an opportunity to have additional info for the board to consider - the interview is available to you. If you live outside of a reasonable distance from the Academy, the admissions department can connect you with one of their admissions partners to conduct the interview. From an anecdotal evidence perspective, not many candidates choose to interview - but it is a personal decision and something you should discuss with your AO.
3. Only your AO can answer the question of "is it too late" with regard to the timing of an interview.