Hi S.,
That's a tough question, because - often if a child begins to get ear infections before 6 months, they tend to be prone to chronic ear infections (one after another). A second challenge is that sometimes children carry fluid in their middle ear with no symptoms, so it is difficult to know it is there. No infection is present, so no fever.
As a speech-language pathologist and mother, I can tell you first hand (professionally and personally) that these conditions often lead to some speech and language issues (usually articulation). I don't tell you this to scare you - I just hope that if you do hear things that your gut tells you are not quite what you think you should be hearing, that you will seek intervention. Please do not follow the "he's a boy - I'll wait" philosophy.
Again, speech therapy is not invasive, and my youngest one (who also started the ear infections at 5 months) started speech at 17 months. She is in kindergarten, and still battles with fluid in her ears.
Your child is fortunate that you are concerned and visiting the doctor as necessary. Good luck! I know what a challenge those ears can be!
S.