Your first set of deals totals 9, the second second of deals totals 15. Where do the 6 deals come from?
Generally, if you want to visualize how many deals entered a stage in a given month, there are two ways to go about it:
Deals get an ‘Entered stage date’ property value per stage. That means that deal stage move information is not stored within one property but as many properties as there are stages. That, in turn, means that you would have to create one report per stage as HubSpot only accepts one date property per visualization (except for tables). Deals that entered stage 1 per month, Deals that entered stage 2 per month and so on. You would do so under Menu > Reports > Reports > Create report > Single object > Deals.
In the sales analytics (Menu > Reports > Analytics tools > Sales analytics), there are various reports that go in a similar direction, e.g. Deal pipeline waterfall and Historical snapshops. I’d recommend checking whether these out-of-the-box reports fulfil your requirements.