I don't think you'll be at a disadvantage. From the looks of it you have everything you need to articulate why you'd be a good fit for those 3 specialties. One question that you may have to answer is why fellowship vs. residency/academia, which you can address with your first cycle. For clin dev vs. ops vs. pharmacology, differences from what I've gathered (perhaps you know more) are foundational vs. executional vs. mechanistic. There's overlap but clin dev focuses on CRF/protocol development/writing and med data review while ops is about logistics of managing study sites - planning, initiating, maintaining, closing - according to protocol. Pharmacology self-explanatory - PK/PD, dose escalation, POC testing, etc. Perhaps you can examine your strengths/weaknesses/personality to see what the best fit is from a skill/disposition standpoint. I'm guessing your rotation is at least somewhat related to those 3 specialties, but if not, doesn't really matter, as you can speak to people outside your dept. to get roped into projects if you convey your interest (under the initial guise of networking and learning about their work etc. etc.).