Your observation is EXACTLY why I don't agree with all those "no point in buying a light bike until I lose weight" people... I'm not advocating gram counting but I think that extra weight on the bike itself is very noticeable in comparison to something a bit lighter.
How many gears do you have? My kids bikes have a crazy low granny gear... legs spinning wildly and they barely move. You can ride up a wall on those things. looking at the rear cassette on their bike, you get gear, gear, gear, gear, gear, gear, DINNER PLATE and it's kind of funny.