Confused!

Hello, I wonder if anybody can give me a bit of advice/clear things up for me. My partner and I started trying to conceive at the start of Feb 2012, I was taking Logynon for approx 6 years, and took my last pill around January 28th 2012. I started bleeding after a few days of stopping the pill, which I assume was withdrawal bleeding, then went on to have periods starting 5th March (ended on 9th March), 17th April (ended on 22ndApril) and 24th May (ended on 29th May). I did not have a period in June, and so far have not had one in July. The dates were a little off as I was used to a 28 day cycle but regular-ish all the same. I have taken several pregnancy tests, all of which have come back negative. Ever since starting my periods around age 12 I have never missed one, and never been late. Before taking logynon and during taking logynon I was always regular as clockwork with a 28 day cycle and wasnt surprised my periods seemed to regulate quickly. I am concerned about the sudden missed period, and wonder if is worth visiting the doctor? I realise it is very early days but given my cycle has always been very regular it is strange for me! Any help on this would be greatly apprieciated, as I am new to all this! x