Is it IC or OAB?

I am a healthy 32 year old woman and have had issues in last year with urinating a lot during the night (every night).  The key is it only happens during the night or when I nap during the day, no other problems during the day.  Also, I have had no pain in any way with my urination issues.  What happens is that when I lay down to go to bed (also to nap) I will get up between 3-7 times to go before I fall asleep then the same thing when I wake up (if I lay in bed and don't get up right away).  I will also get up 3-5 times after falling asleep to urinate.  Sometimes I don't really have to go I just feel a serious urge to go, I always get up because I never know if it is an urge or a real need to go.  On a bad night I have had to get up 15 times before falling asleep.  

I recently moved and am seeing a new doctor (OBGYN), I told him about this issue and he immediately said it is Interstitial Cystitis and did a bladder installation on me right there.  He told me to go home and research it and come back at the end of the week for another bladder install and then will give me drugs to help, Elmiron and Elavil.  I researched and it seems like most people with IC have pain so I was very confused because pain is not at all my issue and never has been.  Also, I only have the issue when I lay down and at night and with IC it seems like it would happen at other times.  The drugs concerned me because it seems Elmiron is a blood thinner and Elavil is a anti-depressant and both are given again for pain.  I researched the doctor more and it seems his research is in IC.  My concern is that I have an overactive bladder and don't want to take a blood thinner, anti-depressant and go through painful bladder installations when IC is not my problem.  

I am going to talk to him again next week but wanted to see if I could get some feedback from someone else.  I did some research and I am wondering Detrol and Ditropan for OAB with be a better option.  

Thank you for your help!!
Kitty