If you want training advice, then getting faster generally involves increasing the load that you place on your body. I.e. more volume or more intensity, or a combination of both. If your riding amount is the same as it has been for a while, then my guess is to go with intensity, as it sounds like you have a decent amount of volume, and probably not so much capability to increase volume further, but I appreciate that adding intensity to a commute is a recipe for disaster, both in terms of accident risk, and the lack of recovery, as you have to do it again the next day. Best guess would be to add some intensity at the weekend, or if it is possible maybe a bit onto you last ride of the week home. Something like this is short and sweet, and doesn't add much time to your ride, and you only need a short safe bit of road to do it on.
I don't know mcuh about supplements, but I think that is a BCAA, and there are people who swear by them. If you really want to lose weight, then if you were following the Wiggins debacle, then obviously Corticosteriods are the way to go, and not forgetting the AICAR and GWi1516, but no-one of course uses them; pro cyclists are just magically thinner than when I was young through advanced understanding of nutrition...spot the sarcasm.