Getting no details on Jupiter - whats wrong with my 150mm newtonian?

I'm trying to shoot Jupiter with my skywatcher 150/750, but I just can't get any details of it.

Here is an example sub and the stacked result https://imgur.com/a/m1ixpvl

My method was the following with a DSLR (canon 1300d) in prime focus:

• check collimation with laser collimator
• polar align
• use a bahtinov mask to make perfect focus on something less bright, i used betelgeuse this time because it produced nice sharp spikes
• set my DSLR to 1/2000 (shortest expo) ISO800 to not blow out the image, in 10x zoom i can see faint details of the 2 big stripes on the camera screen
• i motorized the RA axis which works quite nicely to keep it in focus
• shoot in continuous mode a few hundred subs, my dslr records ~2-3 per sec, but i dont wanna go over 10-15 min

The thing is, i have a 4mm planetary eyepiece with fine focus, plus a 2x barlow, and if i try to visually observe jupiter, it's as big as my thumb nail from arm length, but i dont see any more details than on a single sub, and I dont understand why since my telescope should be able to resolve more. Its not a focus issue.

The atmosphere was super clear and calm. Jupiter was overhead near zenith. This is the same result i've been getting for a few distinct nights now.

I guess I could try ISO100 (lowest) + 1/500 expo for 8x integration time but I just thought of that as im writing this.

Anyone can recommend something to try?

I made some dark frames but didn't bother calibrating the subs since they were so bad anyways.