Getting ready to start carrying, advice on weapon size for a slim guy & a good starting weapon for a lady

Hi all, been lurking for awhile, but this is my first post. I've never carried, grew up firing long guns, fired M9's in the army, a buddy gave me an SR40c awhile back, and now that I am at least semi-permanently settled in Florida, I'm ready for my carry license, but not sure if I have the right weapon.I am a 5'10 male and I fluctuate between 145-155 lbs. Basically, I'm slim and athletic, I sometimes gain a slight belly but usually take it off quickly, and I don't build much muscle mass. I also habitually wear relatively slim clothing, jeans, t-shirts, button ups (tucked & un), suits. Given all the above, I am concerned about actually being able to conceal a weapon, and inclined to think that the difference between by current weapon and something like a 9mm shield or even the sr9c might be critical. Any other "athletically built" guys out there that can share their experiences?As an aside, I've also (after much lurking/researching) come to the conclusion that the round size of a .40 is more likely to be a disadvantage than an advantage, so that is also playing into my thinking a bit. Though I'm having trouble accepting that fact emotionally...As background, I think that AIWB would be best for me, seems easier to conceal & access & I am confident in my ability to mitigate the risk. My budget is tight right now, so I would rather avoid buying equipment for my current weapon only to have to turn around and by new stuff for a new weapon a short time later. Mainly, I'm trying to decide if I should sell this and buy a 9mm. If I don't, I'll be trying to figure out the best holster/belt. for what I have. Thanks for the help!On a somewhat related note my girlfriend (has only shot or handled guns a few times) has been interested in carry for awhile, and has become more so recently (we live in Orlando). And recommendations on a good starter weapon for her? She's in her early 20's, slightly shorter than me and maybe 120, also athletic, relatively strong compared to most women. I'd like to recommend something to her that she can train on at the range for awhile, then use for CCW. I'm thinking that 9mm would also be the best choice for her over any smaller calibers, but I would love to her what the ladies of CCW & men who have experience with such things think.Sincerely,20questionguy. via /r/CCW http://ift.tt/1sLu19D