Ballastbelly - it really would be better if you waited until you've gone through your course material, and talked with an Instructor, before you keep running scenarios though your head and make yourself worried. Most of the questions you've posted recently will be covered in your class, and the Instructor isn't going to let you get yourself in a bad situation.
Okay, back to your question:
The answer would be; No, you won't get "bent" from the pool sessions. However, if you fail to ascend slowly, even from a 15' pool, you could experience problems other than Decompression Sickness (DCS / The Bends). DCS isn't always the bends, because not all of the problems result in painful joints keeping you "bent" over. The rate of N2 absorbtion in a 15' deep pool is very slow, so your RNT won't be a factor for your pool sessions.
What CAN happen during your pool dives is called a Lung Overexpansion Injury due to NOT keeping your airway open (breathing). People think because it's shallow, you aren't in danger, but in reality, you're more likely to have an over-expansion injury in a pool than from changing your depth by the same amount during an actual OW dive. It's due to the percentage of change compared to your current depth.
You'll learn that a volume of gas (lungs) will be inversely proportional to the charge in the pressure. Pressure down --> Volume up (expands)
Pool: Change from 15ft to 5ft due to buoyancy issues, and that's a 66.7% change in your surrounding pressure for just 10ft.
Open Water: Change from 60ft to 50ft due to buoyancy issues again, and it's only a 16.7% change in surrounding pressure for that same 10ft.
The volume of air in your lungs will expand due to the drop in surrounding pressure, and if you hold your breath, that expanding air has nowhere to go except for through the alveoli (lung tissues) and into your chest cavity, or into your bloodstream.
