Hello everyone. I am going round and round in circles reading running articles so I would love it if anyone has the time to advise me on what's the best course of action. Sorry it's a bit long!
Background: I am in my late forties and up until a year and a half ago I hadn't done any real exercise since school although I walk everywhere. First wake up call was when I was spectating a badly-managed sports event and there was almost a crush in the crowd. People were climbing over the barriers to avoid getting squashed and I couldn't lift my leg up to get over it!! Luckily someone offered to help me. Lockdown was a second wake up call - after months of not moving at all I was shocked at how unfit I was. I literally couldn't run for the bus - or easily crouch down to retrieve things from under the wardrobe etc. I did C25K and amazingly started to like running. I decided that by the time I turn fifty I would like to be fitter. To that end I have started doing 20 minutes of yoga a day and running 4km 2 or 3 times a week.
The problem: after the initial success of actually completing C25K I am not actually improving! I am really quite slow (1km in 7:30 minutes more or less). I still find it hard - I definitely can't chat and run like many of the faster and older runners I see do. The yoga is helping with core strength but I am still quite puny! After running I am as red as a beetroot and people actually stop me to ask me if I am ok. 
If anyone has any suggestions for running or anything else I should do I would be very grateful!
TLDR: I am almost fifty and not fit despite running regularly - what else to do?
Bonus question: I don't have a fitbit or anything like that but I do have a birthday coming up - costly gimmick or useful tool?
Thanks 

