Here are two ideas that I've used on numerous occasions to add weight to gain depth or improve the action.

I carry a selection of tungsten beads of various weights and sizes which can be threaded on the line prior to tying on a nymph or wet fly. Just allow them to slide down the leader and cover the eye of the hook.

After tying on a fly you may notice that it doesn't swim as you might have hoped -- it's upside down, rides on its side, or whatever. Adjustments in subsequent flies like hook size or material content/placement can be considered. But, if you want to fish it now there is a quick fix that may work. A small amount of very fine solder wrapped on the bend of the hook and held in place with a drop of super glue is worth trying.