getting kind of frustrated with my lack of progress on pace

I've been jogging at least 3 times a week for several years now. I don't really push for mama speed when I am out there but I have been getting kind of irritated about the fact that I seem to get winded easier despite the fact that I have been kind of working at this for a while now.

I'm sure that some of this could be because of phone error but my last phone was suggesting that I was moving quite a lot faster than I am now. A few seconds here and there would be acceptable but if this phone is to be believed, then I am a full minute and half SLOWER per km than I was two years ago.

Maybe I've gotten bigger from all the weight training. I don't know what is going on

I don't normally look at my pace or even how far I have gone when I am actually running, I just kind of go with the flow and see what happens. I am at least somewhat familiar the way I am going though since it is a similar path every time. I don't feel like I am moving super slow.

The start of these things is the same. I get a bit too anxious at the beginning and go quite a bit faster then than I end up going for most of the rest of it. I know I am not fast but I really don't feel like I am a 9 minute per km guy.

I don't know how I could improve this. Perhaps I should start looking at my diet to see if I am not giving my body the correct fuel. It just doesn't make any sense to me that I would get slower the more I train.