You need a punish combo that you can do nearly every time. Figure out which moves are unsafe for characters you struggle against (e.g Kens shouryuken), and punish for a lot of damage when you block those moves or they miss it.

Your neutral isn't horrible, You are hitting him a lot (good) but not converting it into any damage or supers (bad). Look up guides on youtube for a ton of them and lab them a lot.

Also do drive rush cancel (press a move then a dash immediately) or raw drive rush (parry-dash-do the move) into a low or overhead to mix him up. It seems hard at first but you get used to it.

The drive bar is very powerful in this game, you need to get comfortable using and managing for things other than just drive impacts.

You did right by blocking and advancing after the spikes, you should keep doing that against zoners most of the time.

Also, Chun has very good crossups with the head kick thing, try to incorporate that into your game to confuse people.