irregular bleeding help

Lisa
Hi,
I am BF but not exclusively & I was put on Cerelle in December but I continually bled on it. I don't think it helped that I forgot to take it a couple of times. But anyway I decided to come off it on 18th Jan as the bleeding didn't stop. I then bled for 1 whole week afterwards.. 
I then didn't bleed for 8 days.. and now yesterday started bleeding again.. could this b my natural period? I'm worried as I've never had irregular bleeding before & I'm always worried it a serious illness! 
My GP thinks it's dysfunctional bleeding but I'm still scared! I had a smear done almost 2 weeks ago anyway as I was due one but not had results back yet.
Anyone else experience this? Or had more bleeding while BF? 
Thanks