Should I use “modes of operation” for a single block of data? I am using AES to encrypt my data. I have only 128 bit block that I am encrypting using AES. I am using AES in CTR (counter) mode, since it is always to advisable to use block ciphers along with modes of operation… but I think this is generally the case when you have more than one block of data.

Should I also be using AES in Counter mode to encrypt a single block?
And does AES of single block in CTR mode enhance my confidentiality?
Even though you are only encrypting one block at a time, think about what would happen if your input data happens to be the same as a previous encryption.  Even though you are encrypting the blocks days or weeks apart, plain encryption (aka ECB mode) would have the same problems as usual.  Counter/CBC/... are designed to avoid that problem.  If you know the input data won't repeat (sequence number, etc. as part of your data) then you won't have the repeating blocks problem of ECB where identical plaintext, when encrypted with the same key, always outputs the same ciphertext.