Adelenelynch there have been many threads previously started around pool training and the general gist of them is nothing is ever foolproof or completely safe.
There is a always a slim possibility that even sticking to a very conservative and known regime well within your limits that factors you were unaware of could potentially lead to you B/O.
Another problem with pool training (not so much your case) is that if something does go wrong, it often impacts all free divers practicing at the pool.
All the usual rules apply regarding hyperventilation or unusual breath-up applies (as in don't do it), if I were you, and had the time and opportunity when I could train with buddies like you stated I would just train with them.
It comes down to how much risk you're willing to take and a large amount of common sense. There is no concrete answer for 'is that alright?' for you, it may well be. Just as easily though, it could be your undoing.
You have to realize just because it was fine yesterday or the dive before doesn't dictate that it will be fine this time around. Too many variables to be completely certain of anything, which is why people have buddies to account for that time when it isn't ok.
I'm usually a lurker here, but i've read quite a lot of threads on this sort of thing. It's usually agreed to be fairly bad practice, but for some people who have no other alternative and have read up on all the potential issues they can choose to do it as a responsible adult if they wish.
If you must, surely take all precautions as is realistically possible.
Guidelines vary but they're always stick to very conservative distances/times, have long correct (no moving etc) rest periods (i'd take my sweet time if I owned the pool, as you do) and never dive if you've been sick or are even slightly off feeling. Don't work to goals/targets but rather what signals your body is telling you. I'm not sure if it would be worth having but a blood oxy saturation tool might be a worthy investment to ensure your stats are just the same as after the previous rest period? (it probably isn't nearly that simple however, trux etc would know)
over and above that, go check out what some of the more experienced guys have said. Search will help you there on specifics, but peoples abilities vary so much even those are only a guide.