First Bean to Bar Batch: troubleshooting flavor

I just finished my first bean to bar batch, and I'm afraid I under-roasted. What would be the clues that point me in that direction? I roasted to a nice brownie smell, but after winnowing and starting the refining process I found that they smelled and tasted incredibly bitter/astringent. I read (too late) that some recommend roasting beyond the first phase of brownie smell through a "vinegary" phase, and on to a second "brownie" smell. I conched in the premier grinder for 24 hrs and some of the astringent flavors dissipated but not very much. These are the"mixed bag" of test beans from chocolate alchemy - a cheap option for my first batch but unfortunately cannot compare tasting notes to John's suggestions that are offered with his other beans. In the end, it is sort of good, very bitter and tastes a bit like traditional Baker's baking chocolate. 70% cane sugar. Even if it's not exactly good as eating chocolate I'll break up this first batch and save some to compare to future batches.