Thanks for the query.
Usually the size of genital organs won't influence the fertility
The count and quality of the spermatozoa
is more important.
Stress and strain and medicines can affect the hormonal levels and can alter the menstrual cycle.
So you once consult gynecologist and get examined to find out the cause for irregular periods
After regularization of your periods you can track ovulation and plan intercourse around that time that will increase the possibility of pregnancy
For more details you can ask me through: http://www.healthcaremagic.com/doctors/dr-sree-gouri-sr/63429