pin pointing problem!!!

[yarisgirl77]

I have a 2007 yaris sedan

the alternator was changed last December 24 and two weeks ago while driving my battery light was blinking while I was heading to work... on my way back it came on after 15 min of driving and stayed just as I pulled into the driveway I had a hard time turning the steering wheel... The next day it wouldn't start so my dad checked the battery as he assume because it was the problem as the alternator was just changed .... went for a cruise everything was fine that night went to work it was okay on my way back it started again ...after a week thinking it's just the lights as nothing was going wrong we let it go...

on my way back to bring my son home car battery light stayed on after 30 min of driving .... followed by the air bag light we double check the passenger seat belt everything was fine then losing power of my speed gage and the fuel one and then came back to say I had no gas and my car starting to lose power and it stop on the side of the road .... tried to start it several times and couldn't after going to make a phone call and getting guys to come and see it my car started in one shot but still have battery lights on ... was able to drive it for 1 1/2 to go home but when I went to go somewhere and end up parking the car it died again .....

all we can think that we have done is played with the stereo ac and heat

do you guys think I have a short somewhere ?

ps I had a mechanic look at it fast and he said my alternator and battery is okay and looks like its charging