Initially one of our DM's had the same problem. He was essentially giving us one or two items per level, which meant by level 3, we were way under the recommended limit. But at low levels, this is hardly an issue. Everything you fight is meant for lower level characters anyway, and the difference a +1 item plays is not fealt very heartily. At level 4, perhaps after some prodding from us, he decided to open the flood gates a bit and equipped us up to where we should be. Now at level 6, I'd say we are doing fine.
While ignoring the treasure guidelines completely is not a good idea (a level 18 paladin fighting in mundane plate armor would be pretty terrible), it's possible to fix a mistake like this at low levels without too much impact on the game. So tell your DM, point out the DMG bits, point out the math, and maybe point out this thread, and things can get squared away.
In my game, I sometimes (intentionally) starve the players for a level, and over give the next level (depending on the levels of creatures I intend for them to fight), using treasure as kind of a knob on the dial for my encounter designs. Some levels I just give defense items, some levels I just give offense items, sometimes I'll insert an item a character is in dire need of.
The DMG guidelines are at least the median that should be used when rewarding treasure (or one of the "low treasure campaign" guidelines can be followed of course).