You cannot merge Steam accounts unfortunately. I have 2 accounts also and it can get annoying switching back and forth to play certain games, but I'm pretty good at it now so it's not so bad, haha.
The only decent aspect of having multiple accounts is that if a game is shared between the accounts, say Half-Life, then you only have to install the game once on the hard drive, as the other account will just use the core game files from the original installation.