Python datetime formatting for yyyy-mm

Question

Im have a csv file with date data which is formatted as 'yyyy-mm-dd' or 'yyyy-mm'.

When i import the csv file and convert to a dataframe, the datatype of my date column is object. Im trying to convert this to datetime, but whenever i do, the dates which are formatted 'yyyy-mm' get converted to format 'yyyy-mm-dd'.

How can i convert the data from object to date but preserve the 'yyyy-mm' format? Ive tried the methods 'pd.to_datetime', 'strptime' and 'strftime' which all result in my data changing to 'yyyy-mm-dd' format.

Thanks for your help