Suggest Treatment For Weak Erection Problems

Hi. Lately, I've been experiences weak morning erections and weak erections in general. They aren't so weak as to not allow for intercourse, and my girlfriend claims that she doesn't notice. What I would say is that the shaft itself is hard, but the bottom of the shaft used to get a lot harder, and the head used to get a lot harder. Also, orgasms lately have been good, but not the explosive feelings I used to get. A few months ago, I had two of my first "lost" erections during intercourse. I've had a few of these bouts since. In addition to all of this, I've found within the last two weeks that my sex drive is almost none. I used to want sex, and be able to give sex, 3-4 times a day, as recently as four months ago. As far as lifestyle changes, I recently started a desk job after working manual labor jobs. I'm 23, and I'd like to believe I'm overall very healthy. I do smoke and drink to excess on occasion, but as recently as a month or so ago, I could come home from the bar on a Saturday night and still get a raging, throbbing erection. I had a pretty bad bout with the flu a little over a week ago, from which I still have a cough, but I'm not sure if that has anything to do with it. It was happening a little before, I think. I'm just confused. This happened once before in at the beginning of January, but it cleared up. I'm confused. I've put on maybe 5-10 pounds over the winter, but I'm not sure if that's it either. Please help! Do I have erectile dysfunction? Will it always be this way? My penis is also smaller than I remember.