Would you mind sharing when you last checked your status before this evening was? Information had been discussed about statuses changing on Tuesdays, and so if you checked your status yesterday and it changed just today, that would change things maybe.
As for what you can expect as being on hold - you can expect that there are no hard rules about it haha. There are all sorts of sources with sometimes conflicting answers, but here is the general consensus. Now that you are on hold, it DOESN'T mean you are on the waitlist, which is ranked. Before the rankings are determined, you could be accepted, you could be rejected (this might not be a possibility, seems slim if it is), or nothing could happen and you eventually get ranked. If you are ranked, you will probably find out your rank sometime between May 15th and the beginning of June. I can't really remark on percentages, mostly because there are various methods of deducing exactly how many people get put in that category, but I can comment on how many are eventually accepted off of the ranked list. Some years, which seem the normal amount, around 60-90 are pulled from the waitlist, a very large number. Other years it is as low as 34, which is still a respectable number. Keep in mind that of the approximately 550 that are interviewed each year about 220 are accepted. I'd guess that a large portion of those interviewed are put on hold, moreso than either of the other two outcomes, probably combined (not optimistic I know, sorry).
So long story short - try not to get your hopes up until you see your ranking (which I'm guessing at this late in the cycle you have a much higher chance of getting ranked than either of the other two outcomes), and then STILL don't get your hopes up unless you have a very low ranking. I know what it feels like to feel like you did horrible in an interview and wanting SOOO badly to get your hopes up and look forward to a school you really love, but try your best not to dwell on it. There is simply nothing you can do to change your situation right now, so try not to worry about it as much.