Hi Shasi, 
Let me start by saying that even though 7 yrs is a long time to wait for 
pregnancy, please don't lose patience & hope. We can only make way for pregnancy, but finally the ball is in God's court. 
I will just give a checklist for you to find any reason, see if you have missed anything. 
Husband- 
Semen analysis at least 2-  done 4 weeks apart preferably in an 
infertility center ( examination done by andrologist), Blood sugars
Wife - Blood Sugars, 
Thyroid profile          
Ultrasound scans to evaluate 
Uterus , Ovaries & adnexa
          Confirm tubal patency- most important- Tube is the connection 
          between uterus & ovaries( the bridge where sperm meets the egg & 
          forms a baby) this is size of hair follicle & cannot be seen on scans.
           If all this done & found normal , nothing can stop a pregnancy with   
           God's will
Don't worry about those follicle not growing , I don't think that IUI cannot be considered. 
Proper IUI is start 
Ovulation Induction medicines along with Hormone injections for the follicle to grow daily or atleast on alternate days. When the follicle is of right side , give injection for it to rupture & when it does , do IUI. 
I simulate it to , if a seed is sown , you need to water it every day , not just once in a while. So that's the reason the follicles didn't grow. 
If rightly stimulated with correct dose , they will rupture on time. 
May be if you complete the investigations & do a PROPER IUI , you shouls get a positive result
Hope I have clarified your queries 
All the best.
Dr.Balakrishnan