Im trying to bulk up but dont feel like im spending enough time working out. My question is how often should I workout without overtraining. Right now im doing three days a week. chest / shoulders, arms / abs, and legs one day. could i work out my chest or arms again in the same week? thanks

yes. Twice per week would be fine. I see you are slacking on the back... I wouldn't. With a killer back your overall appearance will be better. Not to mention that antagonist muscles (back to chest) are key to avoiding future injuries.

Everybody is different, and after a while you'll feel when ur body is tired or healed.
ppl will tell you to train like this or that, with so many rest days. But if your not pushing yourself hard you can train everyday. If you rip urself to bits you can only train once a week.
If you write down everything you do and compare it all you will get a better idea of how long it takes ur body to recover.

Sometimes you might train a muscle hard and its fine in 2days, but if ur not sleeping or eating right then it could take 4-5days to recover.

Sorry I cant be more specific, but it's best to work it out yourself than have some1 tell you, cos it may not suit you or ur lifestyle.

Some ppl may not agree but i got great results this way...
Instead of doing any particular body part, I have pushing days, and pulling days and core days.
Pushing days- chest, front+mid Delts, tri's, quads,Glutes, etc...
pulling days - Traps, lats, Bi's, calfs, rear delts,etc...
Core - lower back, abs, obliques int+ext, groin.

then on the 4th day you go back to pushing as youve had 2days rest.

a push/pull break up works great for upper body, but for lower it'd be hard to work in compound leg exercises, so maybe intead of ..

"Some ppl may not agree but i got great results this way...
Instead of doing any particular body part, I have pushing days, and pulling days and core days.
Pushing days- chest, front+mid Delts, tri's, quads,Glutes, etc...
pulling days - Traps, lats, Bi's, calfs, rear delts,etc...
Core - lower back, abs, obliques int+ext, groin."

you could try...
push
pull
legs/core

I currently do a push / pull / legs & core 6 days on 1 day rest. Soon I am switching to 2 days on 1 day off, 2 days on, 2 days off mix... I change my workouts every 4-6 weeks to try and trick my body.

Also, I take 1 week off after ~4 months of weight training. This helps my body to heal any outstanding issues and gives me a mental break.

I haven't weight lifted for a year (until 2 weeks ago) because I was training for a marathon. This year, I am training for my second marathon, but I am going to incorporate heavy weight training and see how it goes. I am tracking everything with detailed logs. Logs help me to see what things a re working and how efficiently.

I agree with manofKent about everyone being different. It is essential that you pay attention to what your body is trying to tell you.

-Rip

I do include legs in my push or pull days.
I see a leg curl as a pull, calf raise a a push, and so on.

I like dont like training legs and core on the same day i do a long run on core days.