I'm not quite sure why Tigerle thought I'd be helpful ... certainly not in interpreting the IQ subtests as I'm no expert and despite being a bit of a numbers geek harbour a lot of skepticism about IQ at the best of times. I really have no idea whether the discrepancy in your dd's subtests could have anything to do with her relative weakness in math.
But I am a homeschooling mom of a bunch of gifted kids, and my ds did have a similar degree of discrepancy. He was assessed for dysgraphia upon entering the school system at the 10th grade level after a lifetime of unschooling, and they did a FSIQ as part of that -- I had no idea this was part of the LD assessment, but whatever: he found the process fascinating, and enjoyed hearing statistically derived comments about his certain learning preferences. His low score, however, was on visual processing speed. I was confounded by it, since he is some sort of expert in 3D mapping in computer game modding, and his reaction time playing video games is so incredible. But it did make sense of his anxiety overload when trying to sight-read music: he just couldn't process the pitch information fast enough to keep up with the beat. He's extremely strong in language and reading, but also very strong in high school math (wasn't so keen on K-7 arithmetic stuff on paper, but has come into his own as things have got more abstract). So he's different, but the amount of discrepancy was similar, and he was homeschooled for many years.
I totally get what Tigerle is saying about a not-so-obvious problem easily being overlooked in homeschooling because it's much easier to compensate. However, I'd put a different light on her interpretation. IQ scores, if accurately measured, are supposed to remain fairly fixed over time, so if a child has a significant are of weakness, you're not going to cure it: you're looking at developing compensatory strengths, alternative ways to learn, and various other work-arounds. I'd say that homeschooling often allows the discovery of compensatory strengths and coping strategies to occur naturally.
In my ds's case knowing about this gap in scores was reassuring for him because it armed him with information that removed him from blame when it came to certain aspects of his learning style -- or rather it was important when he entered the school system and was being asked to do visually-oriented stuff that didn't work well with how he thought and learned. Rather than thinking "this system of diagramming ideas is stupid and I suck at it and hate it," he could instead think "this system is designed for kids who learn by organizing things visually -- which isn't me -- but I understand why the class is being asked for it; it works for some." Until then I really think it was best that we didn't fuss over any of it and just went with what worked for him, and dug in and dealt with stuff like music sight-reading that was a challenge for him -- in a good way, since it helped him learn to push through things that didn't come easily.
So I guess if I was in your situation I'd rule out the visual perception issues as Tigerle suggested, and if she isn't suffering unduly from finding math challenging, and you're not dealing with school accommodations, I'd just move on as homeschoolers and continue enjoying her strengths and relishing the challenge that comes in her (relatively) weaker areas.