I am still fairly new at diving myself, only have a little over 20 logged dives in the 5 months since certified. My instructor told me I needed 28 lbs so that is what I went with. During my training that was ok.
I am 5'8 and weigh 190 lbs, I have a 7 mil wetsuit, I dropped to 26 lbs after my cert diving with an AL80. Last month I bought a steel 72 and dropped to 20 lbs. Personally I have had no problems staying boyount throughout my dive including safety stops.
IMHO you are better off being a tad over weight and logging each dive and make necessary adjustments to get the most out of each dive.
Be safe, stay wet,
Socaldiver