I don't think Lowdens have an over-long scale, Eleanor. 25 5/8" is slightly longer than standard, but not by much. Guitars with a 14-fret join are often 25 1/2" IIRC, so there's not much in it. But fitting the instrument to the player is always the key, so whether or not it's a "normal" size, "normal" is too long for your hands. :-/
If you like the Lowden sound, maybe the S size would suit you better? 630mm scale equates to a gnat's whisker over 24 3/4". And you'd still have the same kind of Lowden sound that you've enjoyed on the O12. Lowdens come up on Ebay occasionally. You could also join the Cult of Lowden group on Yahoo - they may be able to advise something to help with your O12, or they may know of an S for sale somewhere.
Another thought. The CoL members recommended Newtone strings for Lowdens, so I've used them for a while and they sound great. They're also slightly lower tension than other strings, so that could help per JohnInKansas's suggestion.