Hi Denise,
For a lot of people, talking and running don't come together easily! So first thing is, don't worry!!
Also, talking for a couple of minutes is actually quite a long time, so you may be being a bit harsh on yourself.
However, to get to a steady "conversational" pace, you need to be able to run economically, which isn't always your "slowest" pace.
In terms of improving more quickly, I don't know the plan you are using, (not familiar with the book) so can't really comment. But I do know that over 40's plans tend to be fairly conservative, as it is important, especially in the early days, not to push the body too hard, which can significantly increase the risk of injury.
Having said that, plans are not "one size fits all" so if you post a bit more detail on what you are doing, I'd be happy to follow up -if other forum members don't get there first!
In the meantime, enjoy the running!. Most of my friends (definitely I'm in the over 40's camp!) can't run for 2-3 miles