I second the opinions of Ulf and Jome. 2-3 minutes in depth (it means with effort, not static) is not conservative at all. It is rather a performance on the edge of possibilities - most dynamic and depth dives of top competitors do not take more than that, and not so rarely they end in a samba or blackout (fortunately in safe supervised environment).
If you feel a 2-3 minutes dive as conservative, then I suppose it is relatively comfortable without hard pushing, or without strong contractions. In such case I suspect you hyperventilate rather strongly before the dive. And no, hyperventilation is not only "fire breathing" as many incorrectly think. It is any type of breathing above normal, removing CO2 from your body. It includes deep "relaxed" breathing, purges, and other "breath-up" methods which are mostly just a synonym for hyperventilation.
So if you achieve your 2-3 minutes dives in 20-30 feet thanks to "breath-up", then you were/are much closer to death than you ever want to admit. The low CO2 removes the urge to breath, so you come into the deadly zone of hypoxia without even noticing it. And when you then start ascending, the depressurizing effect suddenly drops the oxygen level in your blood even more quickly, and you can experience so called Shallow Water Blackout quite possibly without any previous warning at all.
Definitely avoid any hyperventilation, and keep the dives in really conservative limits, when diving alone. It may be one minute but also considerably less under conditions. There are also many threads here at DB about safety measures when diving alone. Many such tips are listed for example in this thread:
http://forums.deeperblue.net/safety/...move-mask.html