Replaced battery more than once and have replaced altenator twice in less than a year. What's wrong!

Hello. When I got my car in feb the lady told me she just replaced the altenator. ( Private owner cash sale) In March it breaks down when we go out of town. Battery was tested and dead so we replaced it. Went dead in April was told it was bad altenator, warranty was good on the one she put in so I paid someone for labor to replace the part. In May my gas gage starts moving up and down and then stayed usually around right above a half tank no matter how much gas was in. Right when the gas light comes on car runs out of gas within next couple minutes. A week ago I got up went to get an oil change. Hours later my car wouldn't start. 20 minutes later it mysteriously started but when I killed it again it was dead. When we jumped it off it would crank but very low battery power :  air conditioning face flickered momentarily. Door lights dim. Windows were goin up very slow. But when I went to put it in gear the car died. Took battery to be tested said it had bad cell and replaced it. Everything went smooth from then (about 2pm) until I made it to work (5pm) when I got off work (11 pm) on my way home the Ac shut off the whole face went black. 4w abs light came on. Check engine light flickered on and of a couple times then stayed on. Then car started acting as if it wanted to die. Luckily this was right as I was pulling onto my road I pulled by our curb parked, killed it, and unhooked the main cable wire to the battery (just in case?). Just wondering if this sounds like something u know about. And if so what u think this may cost me (by u of course). I don't have a lot of money. Im a waitress so am saving tips to try to get this fixed so that I have a way to work and get to keep my job! Point of me saying that is just that I need to know what I need to come up with before I'm actually going to be able to get it done. Unless I can pay it out as I make it. Went out this morn rebooked cable to battery and car started. Ac on. Turned it off. Then I Killed it.?
When my altenator was changed the guy that changed it said something ab the fan under the hood was tighter and rotated slower than he had ever seen. Also said when it got hot out and I started using the Ac I may notice problems? Wld that have anything to do with all this or is that an additional problem on its own?