There will always be more to regret than not to regret.
In life we can only be mindful of a tiny subset of possibilities.
The choices you make and have made, leave ample room for regret. Each second focused on regret, the regret can only mount.
'Oh if only I had done so and so instead of this and that.'
There is no reason to believe you would not be steeped in regret, if you had made other choices.
Regret can only exist while looking at the past.
Do you wish to do away with regret...?
Then focus on achieving your future goals instead.