|I agree with Sable--a cat without pedigree papers, or pedigreed parents, is not "purebred," and is therefore technically a "domestic short/medium/long hair." Furthermore, California Spangleds are so rare that Wikipedia actually calls them "extinct," so the statistical probability of your having California Spangled blood is pretty low. Also, despite what your Human seems to think, California Spangleds, which were bred to resemble leopards, are SPOTTED, not striped, cats.
However, you are definitely not some ordinary moggy that has come from generations of ordinary moggies. You have SOMETHING in your genetic makeup, and in the recent past. For the past half hour I've been Googling and looking at my cat encyclopedias, and it's a really close call between Egyptian Mau and Ocicat. I've seen a number of Egyptian Maus (silver) at cat shows, and they tend to be smallish, rather delicate looking cats with skinnier tails than yours, but apparently there is a variation in tail size even among Egyptian Maus (and besides which, you probably have other genetic material as well), so one can't go by the tail.
From your photograph, you look bulkier than Egyptian Maus I've seen, but show cats tend to be skinny (except breeds like Maine Coons, which are bred to be big), and at 8 pounds, you're on the smaller end of the scale for a male cat. Your coloration and pattern would be consistent with those of either Ocicat and Egyptian Mau (as my very limited research tells me), and while your body shape looks more like that of an Ocicat, Ocicats tend to be bigger cats than Egyptian Maus (up to 15 pounds, it says in the book I'm looking at now).
So, what about your head shape and face? Again, it's a hard call...you don't look like the Egyptian Mau I hang out with at cat shows, but upon comparing pictures of Egyptian Maus and Ocicats, I think your face type comes closer to that of the Egyptian Mau, even though the two cats have a fairly similar facial construction. I think if you were a male Ocicat, the pads next to your nose would be more pronounced. In fact, your face is also very reminiscent of an American Shorthair (the pedigreed type, not the average house cat), but the chances of you having the bloodlines of two different breeds are pretty slim (granted, there are people out there who breed two different purebred cats to see what they'll get, and there are always accidental breedings).
On the other hand, when I approached the problem from the aspect of pattern--the spotted tabby pattern being much rarer than the striped (makerel) tabby or the classic (blotched) tabby--I was surprised to find that the spotted tabby pattern is not exclusive to the Egyptian Mau, Ocicat, and a few other breeds, but can also occur in the American Shorthair--although I've never seen a spotted ASH, either in the flesh or in photographs.
In conclusion: As an amateur breed sleuth, I first of all conclude that you are a rarety on Catster, a cat of unknown breed who may very well have a purebred background in the recent past. If I were forced to choose, for the reasons above, I'd say Egyptian Mau. But I am rather curious as to how common Egyptian Maus, Ocicats, and Spotted Tabby American Shorthairs are in the U.S.--and in your area. We live outside the U.S., and these breeds are extremely rare. If one breed is more common than the other, then that would be a clue as to what you are. In any event, you are probably not the result of the breeding of two different purebred breeds--you are either a mix of one of the above breeds with a garden variety Domestic S/M Hair, or--who knows?--that almost unheard of rarity, a purebred cat.
If you want to pursue this matter further and get a pro's opinion, why don't you go to a cat show? Organizations like the CFA (Cat Fanciers' Association) have competitions for non-pedigreed cats in the the Household Pet class. A professional judge will not only be able to observe you closely and examine you by hand (an important way of judging breed), but will also, obviously, know more than I do. And cat shows are fun--in the Household Pet rings the judges are relaxed and interact a lot with the Humans, and ALL the cats get snazzy ribbons to take home to make their Humans happy with! You're such a beautiful boy you'd be sure to wow them!
Anyway, you're a gorgeous cat, you're loved by your family (and Chloe!), you're on Catster--what more could you want!