I went back to implement some of the ideas. I didn't take the fins so I wouldn't be tempted. I did superman glides for about 30 mins and added kicks after that. Here are my observations -
1. During the superman glide, initially the feet did sink within about 10 seconds
2. After a few tries I figured that if I held a tall posture with my arms and feet completely stretched out, the legs weren't sinking as quickly. I was able to stay afloat for over 20 seconds
3. Butt clench helped with stretching out the legs/feet.
4. When I added kicks, it helped me to stay afloat longer.
5. I noticed that even when I was kicking from my knees, I was still staying afloat and infact moving along further. I even experienced the glide like I did when i had the fins on.
Note that through 1 - 5, my feet were not sinking as badly and I was able to maintain a streamlined posture, by and large.
6. Lastly when I tried to inhale by turning my body sideways and putting face back in the water, I noticed that my feet were beginning to sink and hit the floor. (I believe this is where the fins helped by accentuating the kicks and helping my body stay streamlined)
So, based on this drill, I see I can stay afloat but at the same time no. 6 tells me that I need to practice being able to inhale/exhale while remaining in a straight line.
What should I do from this point on?