I think its a funny year and it may still flower for you as it flowers early to late summer. A weekly feed sounds too much to me as it may be promoting green growth rather than flowers? If it were me I would stop feeding but water it well as it like moist soil.

Should I not give it a weekly balanced Miraclegrow feed also? And would a weekly feed of MIraclegrow and tomato feed too much for begonias also?

I personally think weekly feeding is too much, I only feed every 2 weeks as I find some plants just put on darker/green growth and flowers are poor, I also stick to one type of feed all season depending on the plants for Toms its a Tom feed and for perennials/annuals its Miraclegrow. This works for me Jonathan but others will say differently. The instructions on the feed will help you decide? Have you noticed when you are away and dont feed at all or water so much that you come back to more flowers than ever?

Thank you. I will make it fornightly from now on then.

Lets have a pic when it flowers.

Is it wilting between watering, that can kill the flowerbuds before they open.