What Silver said.

How long is your commute? I found my commute (when I commuted, it was 14 miles each way) to be okay, but not great, for club rides. It did not have the intensity of a club ride. If your commute is short, you may find that increasing it and adding days and intensity will help. If you are only riding one or two times a week, that is likely not enough.

It wasn't until I started taking spinning classes that I really improved on club rides. 2x week (intense, with heart rate monitor to gauge effort) really helped, more would have been better but twice a week was all I could manage.

Now I don't commute anymore but I still take spin classes. My early club rides have been slower than I like, but it's early and I just go at my own pace.

Your club rides might just be too fast for you at this point. If your club offers different paced rides, you might want to consider stepping down to a more realistic pace, get stronger there without getting so discouraged, and then step up later in the season. I've found that macho-guy (and sometimes girl) club rides are real hammerfests and don't do me any good.