Congratulations to both of you for 16 days of fasting. All you describe is normal part of fasting with water only. For nausea you can drink warm water like you drink tea, sip at a time. Do some deep breathing exercises for 15 minutes twice a day. No need to force bowel movement. You can try seating on the floor in squatting position for as long as you can and see if it makes you go. But be careful when you stand up from squatting position, stand up very slowly.
Yes, I don’t recommend enemas at this stage, first few days of fast if you had taken an enema it would have been ok. Your body will throw out anything it does not need.