i'm going to be blunt: NO Anabolic Androgenic Steroids (AAS) for you.
and thank GOODNESS you came here before doing anything - i applaud you for that.
before you ever consider aas, you need to think about making yourself aware of how to eat because it'll be a huge waste of time otherwise.
diet is the most key issue to building muscle with or without aas. in fact, it's critical to dieting as well. once you get this in order and you stop seeing results, THEN you MIGHT want to consider aas. otherwise, forget it.
you can certainly post your typical training diet so we can help you tweak it (if you choose to do so, please be specific). it is not a bad idea for you to post your training splits, how much cardio/when, either.
i highly recommend you check the sticky at the top of the diet forum and check out other peoples' diets (do a search). atherjen, supergirl, and fyre have surely posted their cutting diets around here. keep track of your foods and ratios at
www.fitday.com
and about getting cut. why the hell does your boyfriend think deca is for cutting? it's for putting on muscle, and an Anabolic Androgenic Steroids (AAS) that is better used when you know how your body responds to milder Anabolic Androgenic Steroids (AAS) (ie: anavar).
deca has a really long half life (and a shitty rebound for some women). if you get bad sides from deca (deepened voice, hair, clit growth, extreme moodiness, severe bloating), you're fucked by the time you figure it out. it's also definitely not a cutting drug. and surely not something for a first cycle.
and give your bf a smack in the head for me for suggesting something so strong like that to you... and so soon in your training.... patience girly!!!