IF and AND functions request for help

Dear all,

I am trying to learn more on how to use Excel and set some basic plannings on it. Unfortunately, I'm not good enough and for some special requests I cannot find answers in my language. If any reader has the time to reply to my following problem I would be more than happy (thank you in advance)
I have a row with cells with different numbers and under it there is another row that takes sub-sums (=B2+A3). I'd like to make an IF formula under this row to say that
IF 1.0<B2<2.0 write A or leave the cell blank
IF 3.0<B2<4.0 write B or leave the cell blank
IF 6.0<B2<7.0 write C or leave the cell blank
IF 8.0<B2<9.0 write D or leave the cell blank
IF 11.0<B2<13.0 write F or leave the cell blank
I don't need more than 5 different results. I managed to give a solution using the following formula:
=IF(AND(B2>1,B2<2),"A",IF(AND(B2>3,B2<4),"B",IF(AND(B2>6,B2<7),"C",IF(AND(B2>8,B2<9),"D",,IF(AND(B2>11,B2<13),"E"" ")) ))
However, this quite complicated to maintain in the future if you want to change parametrs. Does anyone know a better way to make a function like this working?

PS: I have made the same post a few hours ago but because of my need of getting this thing done immediately I forgot to be polite. I apologize, thank you Ambucias for closing the previous one.