>Let's say the origin of life is a million to one filter, and the successful development of sentience is another million to one filter. Those are actually pretty high odds for those two events, and the combination of those two togehter is enough to make it likely we're alone in the Milky Way.
The Drake equation has 7 terms. When it was first proposed, all but the first were complete unknowns. We're just barely starting to gather enough data to start tightening our guesses for the next two. The rest (which include the two you used) are complete unknowns. You say "those are actually pretty high odds", but by whose measure? There's exactly one data point to support that assertion, and right now that data point suggests that the odds are 100% (with an uncertainty also approaching 100%). We're still decades away from really having the data to assert anything at all about the presence of life outside of our solar system with confidence.
We should be able to make some approximations regarding sentience. If we only consider Homo Sapiens Sapiens, then yeah we only have one data point. If we consider other extinct hominid species, we have more. If we consider dolphins, ravens, etc - we start to have a fuller picture and can make some (at least slightly) informed estimates to that term
You're still extrapolating from a single life-creation event. Until we find a second planet that evolved life entirely separately from Earth, we have exactly zero meaningful information about the genesis of life. Without knowing what percentage of life is roughly similar to life on Earth, we have exactly zero meaningful information about how valid Earth-centric extrapolations are.
The Drake equation has 7 terms. When it was first proposed, all but the first were complete unknowns. We're just barely starting to gather enough data to start tightening our guesses for the next two. The rest (which include the two you used) are complete unknowns. You say "those are actually pretty high odds", but by whose measure? There's exactly one data point to support that assertion, and right now that data point suggests that the odds are 100% (with an uncertainty also approaching 100%). We're still decades away from really having the data to assert anything at all about the presence of life outside of our solar system with confidence.