ovulation

ok so I've been trying to conceive for almost 2yrs now. I'm type 2 diabetic and slightly overweight. I'm on insulin and metformin. I just started using opks and started testing on the 17th my period ended on the 12th. I get a faint line but doesn't seem to get darker as of yet, kinda scared I might not be ovulating. anyone else having this issue? my periods go from 10days to sometimes 20 days long. I'm feeling hopeless and I don't have the money to see a fertility specialist. just kinda want to cry right now.