Most two-piece wetsuits I see rented in this area are actually 6.5mm for each layer, for a combined total of 13mm on your core and 6.5 on the extremities. When I dive wet, I use a 7/5 jumpsuit + 5/3 hooded vest, which gives me 10mm on my core and 5 on my extremities. That's a significant difference, both in raw buoyancy and comfort
(which can certainly affect your buoyancy, especially as a new diver)! Everybody has a different tolerance to cold though, so that may or may not be enough neoprene for you.
I know a few people who are diving very happily with the
Scubapro Nova Scotia in Monterey, typically with a thin shorty underneath.
When I first started diving in Monterey, I was renting a 7mm two-piece like almost everyone else, 6/3 hood, 3 mm boots and gloves (I don't normally dive wet in Monterey now, but use 5mm gloves and 6.5mm boots when I do). Initially I needed 30 lb. (6'0", 175-180) with an AL80, once I got to 25 or 30 dives (about two months after cert) I was able to drop down to 26. The OP didn't say how tall they are, and general build, bone size and % of body fat will affect how much lead you need for the same weight.
After renting both one and two-piece wetsuits I bought a 7/5mm one piece (Pinnacle Cruiser), and used it with a 6/3 hood or 6/3 hooded vest depending on conditions. This tends to be the most versatile combo, is easier (for me) to get in and out of, and is considerably more streamlined than a two piece, and with the hooded vest you don't get that trickle/stream of water running down the back of your neck (at least, not when it's worn outside your one piece). It's been a while, but IIRR using the above combo with hooded vest and an AL80 I only needed 22 later 20 lb., and with just the hood I was using 20, later 18 (or maybe even 16) lb. Later I bought a backplate and wing instead of renting BCs, and was able to drop another 4 lb. or so.
Nowadays I dive dry using steel tanks, and with one of my (very heavy and negative: -5 empty/-12.5 full)) Asahi Genesis HP100s I only need 10 lb. (6 lb. from my stainless steel backplate, + 4 lb. of lead on my tank bands), for a total of -15 lb. empty/-22.5 lb. full (I'm ignoring the ~2 lb. negative added by your reg). Depending on which brand of HP 100 you have (OMS/Faber, PST, Worthington, Norris) you will normally need from 1 to 6 lb. more than I do with my Asahis.
So, for the OP, yes, you will almost certainly drop some more weight as you get more comfortable in the water. And different BCs have more or less buoyancy when empty and some trap more air than others, so if you haven't bought already, rent as many different ones as you can, both jacket style and back inflate so you can compare. In general the back inflates will have less inherent buoyancy than the jacket style and be easier to vent all the air out of (backplate/wing has the least of all/is easiest of all).
HTH,
Guy
