Can't sum up total leads in a month

Can't sum up total leads in a month

Hello,

Currently, I have a problem of not being able to report total count on converted Leads and unconverted Leads. Right now my main goal is to have a report that tells me the total count of new Leads created in a specific month, usually I'm looking for "Current Month"  count or "Last Month" count. I want this report to include leads that have been converted into Contacts as well as Leads that are still in my Lead pool and haven't converted yet. However, after a Lead is converted, it doesn't show up in Lead Reports any longer. Right now, I have to have a report to that sums up Contact Created Date and another separate report that sums up Leads Created that month - so two reports to get one basic piece of data. 

These two reports are not a foolproof method and here's why: if a Lead enters my database in September, and then converts in October to a Contact, that Contact is now showing up as created in October when in fact that Lead entered my CRM in September. My solution to this is to have my own custom date populate upon Lead creation and then map to the Contact and remain in a custom field there so I can get an accurate count. This does not solve the problem of having to use two reports to get one piece of information.