Is this an effective exercise regime for my fitness goals?

[Unadventurous]

I lost a stone a couple of years ago by cutting out snacks and going to the gym 4-5 times a week, and now weigh 8st 9lbs. I lost a fair few inches all over so am really pleased with the way I look overall, but the one area that I still need to work on is my tummy, which has gone from round and firm to flatter but saggy.

So my current weekly exercise schedule is:
30 mins HIIT
60 mins PiYo
30 mins Spin
60 mins Pilates
60 mins Body Pump
Plus I walk on average 10-15k steps a day.

For any fitness experts out there, do you think the above set of classes will give me the best chance of firming up my tum and if not, what would you suggest? Thanks

is it body fat or skin on the tummy? more likely to be diet to resolve it than exercise if the muscle underneath is strong enough

Planking is amazing for toning your tum! I starting planking increasing by 15 seconds a day and got up to about 4 minutes. I definitely saw improvements. Less sugar and refined carbs helps too.

Thanks both, I would say it's a combination of both, so definitely need to lose some fat but there is some loose skin too. I plank in a fair few classes but never for very long so will give that a go.
Diet is pretty good but there's room for improvement, esp reducing carbs.