Hi, and thanks for your medical question on eHealth forum!
There are various reasons for not conceiving this like ovum not being formed, polycystic ovary, hormone imbalance, hypothyroidism, local infection, STD, blocked tubes etc. You should ideally consult an infertility specialist.
The other possibility is semen not staying in after intercourse. If immediately after sex, the semen is pouring out then the pelvic tilt is not right. Place a pillow under the hip while having sex. Let your husband gently pull out. Immediately push your knees up to your abdomen. This will increase the pelvic tilt. Remain like this for 5 mins and then stay in bed with pillow under the hips for 15-20 minutes. Then only remove the pillow.
Try in this position for 3-4 months. Keep a check on your ovulation timing and try close to that several times. Remember in your case both timing and position is important. If still you do not conceive, then consult a specialist.