Ok. First, I think the conversions posted are correct. I have to say though that my Dr. has me on both drugs so you might be on both. You can hope, especially since when you were on both you felt great.
And another thing the fact that the max dose is usually 600mg. makes me so mad! My Dr. insists we can do no more with my medicines, even though I am only taking 300mg a day of Lyrica, and 2400 of Gabapentin. I am sure he could play around a bit more with this. Down the Gabapentin, up the lyrica... something. All he wants to do is push another Steroid injection. The last time I saw him he said: "Well, call the office when you decide you want to do the injection." and walked out of the room. He wouldn't give me a followup! (As he said "we have thown all the big guns at you allready. We seem to be running out of options.") I was so mad.