Formally Dendrobium xdelicatum, a natural hybrid (kingianum x speciosum). If you search it in the Kew database, it shows (kingianum x tarberi), but when you look up tarberi, it is shown as a synonym of speciosum-it looks like they have a little housekeeping to do. The accepted name for the artificially created hybrid is Specio-kingianum. There are three synonyms for this hybrid; I won't list them here for clarity. (If you're curious, check the RHS register). Mine is blooming now too; it's white with a slight lavender blush. I like yours better.