My first beer was overly bitter as well. In my case, I didn't follow the instructions properly. I went whole hog on my first brew pot and got the Megapot 15 gallon because I thought boiling full batches was the only way to go.
I didn't know anything about hop utilization, so I used the full amount of hops for a partial boil in my full boil. Then to make things worse I decided to make my DME addition way late in the boil. I got all the goodie out of those hops, but man was it bitter. I even dry-hopped in the keg to get a little extra hop character so it at least tasted like an IPA.
That one never did calm down. It improved slightly over the next month I suppose, but my brewing notes stated "it's not something I would re-create, or purchase if it was something I sampled."
Eventually, the keg blew and it was all gone. I learned a lot from that first batch.