Switching from Excel to a software - anyone knows an alternative for my needs?

Hello.
I have been using excel for the last 3 months.
Here is why:

I work for a Nonprofit Organization.
We take donations.
Paypal.
Credit Card.
Checks.

We download these in excel.
We then input them into a single excel file.
It's now pretty big and will get bigger.

The problem: so many small issues:
one file has first name and last in same rubric.
Other has them split.
One shows date as XX. XXXX.
Other shows as XX-XX.
One shows state as Xx.
Other as XX.
We need to know how much each person donated. What's the total donated thorough 2013, for example.

and so much more.
It is my job to take all this info and put it nicely into one excel sheet - because we just don't know of any other way of doing this.
Trying to keep track of donors is getting harder. How much they donated, when, how, what's the total donation.

Excel is helping me doing that, but I am not an excel expert, and I am using this forum to figure out formulas to do so.
But it's getting difficult.
Today, for example, I figured out I made a mistake on one of the formulas and we missed out on many donors who were ment to receive a end-of-year gift.
My boss wasn't happy.

Do you guys know of a software that can help us? By software I mean - something more simple, for idiots (such as us)?
Mac, Windows - it doesn't matter.

Thanks a lot - any advice would be great.

benyben, that workbook you uploaded is prety much not worth anything, sorry We need to see samples of what you are working with, to see if there is any way to restructure what you have.

rcm's suggestions are ok for entering future data, but pretty useless for trying to restructure existing data

Please upload a sample workbook with (clean) examples of what you are working with