Iffy is an adjective that comes from the word if. It means that something is uncertain. Here's an example:
Bob: Will you have that report ready for the meeting tomorrow?
Mary: Well, to be honest, it's a bit iffy right now because I'm still waiting for the sales figures.
Mary uses iffy to say that she's not sure.
We use -ish as a suffix to make a time or date less certain and exact.
Bob: How's it going?
Mary: Better. I have the numbers and I should finish on time.
Bob: Great! Do you want to have lunch?
Mary: Sure! What time?
Bob: 1:30ish? I have to be back by 3:00
Mary: Okay, see you then.
Bob says 1:30ish to mean around that time; 1:30 more or less.