Snapping flies means your aren't pausing long enough. If it helps, there isn't anything wrong with watching your back cast to know when the rod is "loaded", then you bring it forward.
The second thing that stood out to me is the fact that you are casting an idicator and a nymph. The trick to this is to take it REALLY easy, because with all that junk on the line it's very easy to get a wind knot or a tangle. Limit yourself to just one or two false casts before dropping it on the water. This decreases the amount of opportunity your line has to get messed up in the air.
The best thing I think you can do is to learn the roll cast really well. You have much greater line control, it's easy, quick, and suits a clunky indicator rig really well. When I was fishing double nymph rigs with multiple split shot, rolling it is the only option. You have better line control and once you get it down, you can drop your fly in a tight area.
Check out you tube videos to learn the roll cast and then I would recommend a free casting clinic. Orvis and other fly shops do them for free, usually so they can get people to buy gear, but it's not a bad way to learn a thing or two. An investment in instructional guide will pay for itself 20 times over in Knowledge
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