Welcome to Susan's Place. Normally I would advise 2-3 years before considering breast implants because breast development can continue over 5 years. The bud that you feel will always remain there and continue to develop as long as you take estrogen. Over time, the bud should become around 3 inches across but would become covered with breast tissue that would make it difficult to notice. The problem with implants at this stage is if your breast continue to grow, the implants may be improperly place and it may require a revision surgery to remove or relocate the implant so your breast appear correct.
Your first set of implants should be size limited. The doctors shouldn't be considering more than about a B or C cup for the first set of implants as it take time to stretch the skin and muscles out. It would be different if you have a reason amount of development as you would just be adding to what's already there.
I am not an expert on implants as I haven't had them but from what i understand there are two ways of placing the implant. One is above the muscle and the other is under the muscle. I suspect under the muscle shouldn't risk growth potential but I don't know about above the muscle. This is something you need to discuss with the doctor before you have the surgery.
As for mood swings, this should be discussed with your endo. There are ways of delivering hormones that provide a consistent delivery. An example is if you are on injections once every two weeks, half a dose every week would even out your levels better. Patches, gels and pills can also provide a constant deliver with the proper dosage schedule but your endo will need to know about the problem in order to determine the correct solution for you.