question about cycle length

I am 10 dpo I tested yesterday and bfn. I am going to test again on wed.  I am wondering if the clomid will change my cycle I think the chart I have is for a 25 - 28 day cycle and usually takes about 35 for af to show for me normaly. However my dr doesn't think i was ovulating, or at least not ovulating every month, before so maybe it will all work out with the schedule he gave me. I have not yet given up, my body is telling me too I think, but It aint over till its over! Good luck ladies!