Not sure If the Nausea is "Normal" but I did have it for approx. 6 mos post band removal, other problems that also felt a lot like Gall Bladder issues but, it did eventually go away. I guess it was from not being able to eat certain foods, and now I it was possible?

If it's persistent( long-term) mention it to your Dr, even your GP can put you on anti-nausea meds( temporarily)

 Not sure about the Weight gain? Again my guess is that your body's metabolism is challenged ( famine mode) with the band and when it's removes your body doesn't recognize it as a good thing and so it tends to Hold on to whatever you give it awaiting the next famine.

Until of course your metabolism resets, but often it's too last and you've regained. Some that I know that have had the band removed have managed to retain some weight loss but it's not with EFFORT, exercise dieting, pills, etc..

 FYI: True Results of San Antonio Texas is CLOSED not sure about the others?? but they have been taken over by South Texas Surgeons

 https://www.trueresults.com/san-antonio-tx

Unfortunately the only thing you can do is to make sure you eat the right things all the time. And keep proper diet long term. 

And measure and journal everything you eat. A bite here and there adds up. No drinking with meals. Plan your meals and snacks. 

Having good restriction is great, but if you are too tight - that may prevent you from eating dense proteins, and slider foods are often the worst for weight loss. 

Even with RNY and a small pouch - I have to careful not only how much I eat - but rather what I eat.  If I eat the wrong things - like carbs, slider foods etc - I start gaining weight. 

When I regained some weight - going back on track was not easy...but after I got determined and followed proper post op WLS diet - I was able to stop the gain, lose the regain and go back to goal.