Thank you for sharing your story. You sound like an industrious, hard worker walking a tight rope. Balance and organisation are the key.
Get a calendar and record your upcoming academic due dates. Now record paid work shifts. Now look at the time left and block off time for study, sleep, exercise, meals, etc. Now consider if your plan is realistic.
If not, you may occasionally need to take time off work to meet your study goals. Or you could consider permanently dropping a shift and cutting the budget. Or you may consider dropping a subject (this will extend your study time but safeguard your health).
It's also helpful to make sure you are using all of your time egfectively. For example, you can use commute time to read/listen to audio tapes or to nap or to just decompress. Think about what works best for you.
Most of all remember to breath. Be kind to yourself. And if things become too much, pop in to see your GP for a chat.
Kind thoughts to you