I would highly recommend flash as well as I believe it would be more beneficial to have more light than to try and and build/buy camera gear to get acceptable results in low light situations. Make sure you get something that can either be taken off camera or at the very least has a diffuser of some sort to reduce the harshness of a flash. Also, spend a little time practicing with the flash understand what you can do with it.

Also, sorry to hear you felt bad about your first results. I remember those photos and they were pretty good. The thing to remember is that as photographers we tend to pick them apart a lot more than the average person. Also, it's all done to help you get better.