I had similar issues with my foreskin my entire life and often considered circumcision. You said that you cannot retract it when erect. So you can retract it while flacid?
Up until about two years ago (I'm 29), I was never able to retract my foreskin at all. I could get a very small portion of the tip out, but that was it. This was a result of not retracting throughout my youth. It was never painful or hindered sexual activity, but was difficult to clean. I basically never even saw what was underneath it until recently.
So about two years ago, when I was coming around to accepting my attraction to men and watching gay porn, I did quite a bit of research online. I learned about phimosis, but also some of the methods used to cure it. I never went to a doctor about it.I almost even purchased an instrument I found online which you can use to stretch the foreskin opening, but opted not to. I soon began the practice of simply pulling the foreskin back, as much as I could (even if very little) without it being too painful, and holding it for bit. I did this EVERY time I urinated, showered, or masturbated, especially during masturbation as semen allows the skin to become more flexible. Saliva helps as well as it is a natural lubricant. Even if it was just very little each time at first, I did it. I never used any creams, but I'm sure that just would have made it easier.
It didn't take long to see some progress, but when I did it excited and encouraged me to continue the practice. Eventually I was able to retract it fully when flacid. I remember one time I freaked out a bit because I was erect and had fully retracted it but couldn't push it back down. A little saliva and some calming down solved that problem quick. It's been nearly a year since I've been able to fully retract the foreskin comfortably while erect, and I couldn't be happier that I didn't go any further with my thoughts of circumcision. It took about a year to get to where it should be, but now it just feels great and natural. Sex is great, and so much better too. I continue to retract it fully whenever urinating or showering, and pretty much always during sex.
Now, if you CAN retract your foreskin while flacid, than you are further along than I was when I first started. Also, my glans is EXTREMELY sensitive, and I'm damn thankful I have my foreskin to protect it. If yours is also very sensitive, keep in mind the length of time it would take your glans to acclimate to NOT having that protection: it's sensitive red surface rubbing against your underwear and anything else it comes into contact with. That sounds a bit painful to me. Dealing with that plus the pain of the circumcision just seems unnecessarily extreme. I recommend what I did, and not getting circumcised. It may take some time and patience, but do as you must.