MySQL monthly diffs - mysql

Question

i spent lot of time to search a solution to my problem. i think i'm near the solution but my final request doesn't work...
first of all, i have a table that represent water index based on 10 minutes sampling.
----------------------------------
| DateTime | Counter |
----------------------------------
| 2020-05-13 15:00:03 | 38450 |
| 2020-05-13 15:10:03 | 38454 |
| 2020-05-15 15:00:03 | 38500 |
| 2020-06-02 12:10:03 | 38510 |
| 2020-06-15 12:10:03 | 38600 |
----------------------------------
Some samples could be not present in the table
so i would like to extract a table to see my consumptions by days, week, month, year
i have found many examples, but none works as i expect...
for the example table above, i expect to get:
------------------------------------------------------------------------------
| fromDateTime | toDateTime | fromCounter | toCounter | diff |
------------------------------------------------------------------------------
| 2020-05-13 15:00:03 | 2020-06-02 12:10:03 | 38450 | 38510 | 60 |
| 2020-06-02 12:10:03 | 2020-06-15 12:10:03 | 38510 | 38600 | 90 |
------------------------------------------------------------------------------
i have writen a query
select mt1.DateTime as fromDateTime,
mt2.DateTime as toDateTime,
mt1.Counter as fromCounter,
mt2.Counter as toCounter,
(mt2.Counter - mt1.Counter) as diff
from WaterTest as mt1
left join WaterTest as mt2
on mt2.DateTime=(
select max(dd.datetime) as DateTime from (SELECT MIN(DateTime) as DateTime
FROM WaterTest as mt3
WHERE month(mt3.DateTime) = month(mt1.DateTime + INTERVAL 1 month)
union ALL
select max(DateTime) as DateTime
from WaterTest as mt4
where month(mt4.DateTime) = month(mt1.DateTime)
) as dd
)
But MySql results with an error saying "Field 'mt1.DateTime' unknown in where clause"
is someone can help to find where i'm wrong ?
Am I on the good way to achieve this ?
(and for sure, if there is a more powerfull request.... :) )