These are classic symptoms of a dying storage device. The 14 shots were (as they always are with any camera) written to the small, high-speed internal storage buffer on the camera. The camera then sends them out, one by one, to the SD card until it has cleared the buffer and is ready for another 14 shots. Slow writing happens when the device is throwing lots of errors and has to try and try again maybe 1000 times before it succeeds. It is quite noticeable on mechanical storage devices (DVDs, magnetic hard drives) where write times are measured in milliseconds (1000ths of a second). If it is noticeable to the human eye on a solid-state storage device like a flash card where write times are measured in nanoseconds (millionths of a second), then the device is really, really sick.

It is possible but unlikely that some of your last 14 shots have been written to the card but are not visible because of the camera having difficulty updating the indexing information on the card which makes the pictures available, in which case they might be recoverable with the right software. Any sane software person, however, would update the index after every write, not do 14 writes and then then update the index entries all at once. In short, it seems most unlikely that there is anything there to recover. In your shoes, I would not spend any money as the chances of success seem poor, but by all means spend a little time on it just in case.

Do not use that card again for anything. It is kaput, useless, gone to God. Throw it away before you get it mixed up with working ones. Or give it as a present to someone you don't like.