Here's alittle more about "lots of and a lot of":

2 a lot of and lots of

These are rather informal. In a more formal style, we prefer a great deal of, a large number of, much or many. (Much and many are used mostly in questions and negative clauses.)

There is not much difference between a lot of and lots of: they are both used mainly before singular uncountable and plural nouns, and before pronouns. It is the subject, and not the form lot/lots, that makes a following verb singular or plural. So when a lot of is used before a plural subject, the verb is plural; when lots of is used before a singular subject, the verb is singular.

- A lot of time is needed to learn a language.
- Lots of patience is needed, too. (N OT Lots of patience are needed, too)
- A lot of my friends want to emigrate. (NOT A lot of my friends wants)
- Lots of us think it's time for an election.

source: Practical English Usage, Michael Swan, Oxford Publishing

Lots of + countable or uncountable noun

- lots of chickens

- lots of money / lots of information

A lot of + countable or uncountable noun

- a lot of chickens

- a lot of money / a lot of information

A lot of means a large amount of something (singular) or number of things (plural).

They are equivalent, i.e., a lot of = lots of

So we can use either expression

I have made thousand mistakes when writing in English but I have never struggled with "a lot". I have struggled thought, with its use and variations, for instance: LOTS OF vs A LOT OF