Follow the dream whilst young, you're dead long enough at the end.
As for the speech issue, it never fails to amaze me how bad otherwise unimpeded people are on the radio. I don't know what your problem is, how bad, nor indeed am I an expert but I wouldn't mind betting with some work, planning and foresight you could beat what you often hear. Don't assume that everyone else is perfect.
Those of us that shouldn't be affected by speech impediments just don't concentrate on RT enough IMHO, how often do we get affected by stammers/stutters/ums and ahs simply but not thinking what we meant to say before pressing the RT button. With your issue I reckon you'd concentrate on this a load more.
True story, flying around a rural part of the UK last summer some guy in a 'Poiper' spent the whole of one of my 15 minute legs constantly talking to 'AyTeeeeSea' about his 'floight'. No kidding I heard 'Cud yew say that agin please, Oi dint quoit cetch it' said six times in response to 'G-ABCD confirm you are remaining clear of parachute drop zone'. Constant requests to check his altitude - from him to ATC - were heard and position reports every minute- no-one else in the air could get a word in edgeways !
If, at the end of the day you can't fulfil the airline pilot dream, at least having a PPL - or even having had a few lessons towards it - will stop you thinking 'if only' when sitting in the nursing home 60 years from now.
Good luck in whatever you choose.