My husband and I moved to SD from Chelsea a little more than two years ago and we are also Jewish. We are not Reform Jews so we don't know of many Reform synagogues. I believe Temple Emanu-El and Temple Adat Shalom are Reform. The Jewish population in SD is not very large compared to NYC and you won't find anything like crown heights or borough park(not what you're looking for anyway) but it is a decent Jewish population. There is a Jewish community in La Jolla(
JCC located here), Carmel Valley, Scripps Ranch, Poway, San Carlos and from what I hear even Chula Vista. There are probably many I'm unaware of. There's an annual Yom Ha'atzmaut celebration in SD and there you can see families from all over the county gather.