need help

I'm 23 years old and we have been trying to conceive for 6 months now with no luck. I know    that for a healthy couple it can take up to a year to conceive but I am so confused!! My cycle keeps getting longer and longer!  When I first started tracking my cycle it was about 36 days long on average. These last three months, my cycle keeps creeping towards 50 days! Also besides the first two months, I can never get a positive ovulation test! I am on cycle day 47 with no period! I have taken many pregnancy test and no I am not pregnant:( has anyone gone through this? Would a DR be able to help me?