The first thing I might suggest is to take the collagen before sleep. As it contains glycine, this has been shown to promote good sleep patterns. The benefits of the collagen are not affected by the time you take the supplement.
Omega 3, ginseng and probiotics are good - vitamin D is fine if you have shown to have a deficiency, otherwise you will be wasting your money. It won't do any harm, but it will not promote any health benefits either. Contrary to what a lot of people would have you believe, the body can allow for its respective levels of vitamin D without supplementation.
Glad that you have started the meditation. I am sure that will help you.
You might find the nausea repeats on you somewhat over the next couple of weeks as you head tries to find the right level of chemicals now the Cymbalta is no longer managing them. We all have serotonin receptors in the inner ear which, when deprived of its usual dose, will often cause mayhem. Any inner ear disruption will cause nausea due to the balance being affected. This is unfortunately, a waiting game.
You will of course suffer as a result of these vivd dreams. I get something similar after periods of severe stress now. It is taking what the brain cannot deal with successfully during the day and processing it at night when you unfortunately do not have control over it.
The ashwagandha you have is the simple root extract - it may well work and if you already have them, then it would be worth your while trying them. The difference between these and KSM-66 is that the KSM-66 is a standardised extract made from a specific part of the root which it known to contain the highest concentration of withanoids (the concentration of the extract). Where any part of the root (and is some very questionable suppliers, other parts of the herb), there is no means of knowing the strength and thus you could be taking different levels with each capsule.
The dose of 600mg may not be enough to have the desired effect and the site isn't quite accurate in telling you to take them on an empty stomach. Ashwagandha needs a little bit of fat to bind to so that they a suitably processed. This can be a small glass of milk, or a piece of chocolate - not a lot is needed, but taking with any larger amounts of food is not going to help.
You do not need to build ashwagandha up in your system much past 2 or 3 days - most people find they feel the benefit from the first dose if they are going to. Start with 600mg, but if you do not get any effect, you can safely increase this dose to three capsules (1800mg). This would be the equivalent of around ~800mg of standardised full-spectrum (KSM) extract.
See how it goes and let us know....