Fed up :(

My cycles vary from 26 days to 31 days. This cycle I tested on cycle day 13 and got a positive opk. I'm now on cycle day 29 and yet to come on my period yet the tests I have taken are coming up negative. Is it still too early or am I out? :( Also the last two months I have had a positive on cycle day 13 with opk but last month came on at 26 days and this month still nothing?! Feeling really gutted and upset x