Seeing this makes me happy because I had a similar revelation a few years ago and it always makes me mad to see people use the glaringly bad justification for being pro-choice which you've overcome. On the other hand, after thinking about the matter quite a bit I still am pro-choice. You say:

On the other hand, as little as it is, it still represents a human life

I think the key word is "represents".

A lot of bad reasoning seems to come from proving a controversial idea can be fit into a category of things that are mostly bad, and then concluding that the controversial idea, too, must be mostly bad.

For example, some people are opposed to a project to genetically engineer diseases like cystic fibrosis out of the human genome, because that's a form of "eugenics". I think this is supposed to cash out as saying that the CF project shares some surface features with what the Nazis did and what those American Southerners who tried to force-sterilize black people did, and those two things are definitely bad, so the CF project must also be bad.

The counterargument is that the features it shares with the Nazi project and the Southern project are not the features that made those two programs bad. Those two programs were bad because they involved hurting people, either through death or through force-sterilization, without their consent. The CF elimination project hopefully would be voluntary and would not damage the people involved. Therefore, although it shares some similarities with the Nazi project and the Southern project (it's about genetics, it's intended to improve the species, etc), those aren't relevant to this moral question and the argument "But it's eugenics" is flawed.

(If you haven't read the 37 Ways Words Can Be Wrong sequence, I suggest that now. Think of a person taking a blue egg that contains vanadium, pointing to a bin full of blue eggs that contain palladium, and saying "But this is a blegg, and we all know bleggs contain palladium!" Well, no.)

The "human life" issue strikes me as very similar. "Taking a human life" is a large category mostly full of bad things. It contains things like stabbing a teenager with a knife, poisoning a senator, strangling an old person in a nursing home, starving a toddler, et cetera. All of these are really bad. They're really bad for various reasons including that they cause the person pain, that they disrupt society, that they violate the person's preference not to be killed, et cetera.

Abortion possibly does fit into the category of "taking a human life." But although it shares the surface features of that category, it isn't clear whether or not it shares the interesting moral feature which is exactly what the whole argument is about. Killing you or me is bad because we understand death and have preferences against it and don't want to die. Whether or not killing a fetus is bad depends on whether or not the fetus also satisfies those conditions - not on whether from a certain angle the problem looks like other cases that satisfy those conditions.

The question isn't whether or not we want to stick the fetus into an artificial category called "human", it's whether it has the specific features that make that category relevant to this particular problem in the first place.

See Leaky Generalizations and Replace The Symbol With The Substance