I think I made a big mistake, your judgement and advise welcome.
I went about building a double-gate for my back yard fence. I was so focused on making the holes position just right, looking out for utility lines, then making the post level and square with the other. I didn’t even consider a 4x4 as being too small. I also am so used to putting in mailboxes I just defaulted to 2ft being enough and only made the post hole about 28-30” deep. Secured in concrete. I was gonna use wheels on each gate to help with sagging. But I fear that’s still not enough. Also it’s just the posts holding this up, I’m not securing it to the house or to my neighbors fence. Do I rip up the 4x4 posts or pray the wheels will be enough to prevent gate sagging.