You should not need to weigh them weekly. If that is giving them more time between weighings than you were, you are definitely overdoing it! I don't weigh my geckos more than once a month, if that.

At this size you are not going to have noticeable growth for several weeks. I know you are worried but it sounds a bit like you are just stressing both yourself and your geckos out at this point.

I am not sure which "complete" diet you are using; some are marketed as complete and are not something I would even feed to my feeder bugs unfortunately. Some are also more appealing to geckos than others.

I was struggling with slow growth rate with animals that were not offered live food. I really do personally feel that they benefit from live food once a week. I start my geckos at about 2 weeks of age with live food. They often don't accept it until week 3-4, but some go after it right off the bat.