I'm pretty sure some of my scans are of the wrong street, in retrospect, because they don't match any of the houses around me, let alone mine. So I screwed up (I did the first scans pretty early on, and I was still a little confused as to the street number, it appears.)
But I got May, 1896 and April, 1909. Here is the house (and carriage house!) in 1896:
And here it is in 1909:
Between 1896 and 1909, the dining room was built out on the north, and the porch added on the east. A larger porch was put on the south side (where the sunroom is now). The 1909 plan indicates that the upstairs above the dining room was frame, not brick as it is now (that's where the master bath is) - but I think that's inaccurate. The attic stairs go up there and the attic structure sure looks continuous. So I think that little square there was part of the original structure of the house, as is shown in the 1986 plan.
The back porch is where there are two small rooms now. Since those rooms are divided by a wall that was external at one point (I can tell from the siding in there), that porch has been removed, then replaced, sometime after 1909. I'll poke around some more later.