You haven't been trying long, so I wouldn't be worried, particularly since you just went off the pill after a long time. I would recommend going on ebay or one of the pregnancy sites that sells ovulation tests and buy some there cheap...they are VERY cheap and reliable. I bought I think 25 test strips w/some pregnancy tests for around the cost of 1 commercial one you buy in the grocery store. Something like this set, for $8.99 shipped:
http://cgi.ebay.com/30-Ovulation-Test-kit-10-Pregnany-Tes...
These are the strips only, like the Dr's office uses, they come sealed in a pkg with expiration dates printed on them. You'll need to pee in a cup w/these but you'll save yourself a bundle and you're gonna need to get used to peeing in a cup anyway. ;) Being PG you'll learn to pee in just about anything the Dr hands you. LOL! I used an old measuring cup - works great!
Figure out exactly when you're ovulating so you know when to start having sex each month. My husband and I wasted a year trying to get PG only to find out that I ovulate much later than we thought so we were missing it. I had to test morning and night to catch myself ovulating (not the norm). We have 2 kids now but it took these tests to get us there. :) If your periods are irregular like mine, this should help you alot. You'll probably have to open that "sex window" up a bit more than most people (like we did) in order to compensate for your irregular periods, and the tests should help. Keep having sex after the ovulation test comes back positive (despite what others have said here), we did this and we did get PG.
Last, relax. Try not to get wrapped up in all the do's and don'ts, it just adds stress and it's so early, you don't need to be thinking about all that yet. Get the tests, have some fun. If, in 3-4 months (after ovulation testing), you're still not PG, then talk to your Dr and start reading up on the extra do's and don'ts.
Good luck! Sending good PG vibes your way! :)