1. ~ばかり (Only, nothing but, always...)
N + ばかり
Always doing ~, and nothing else. Often used to talk about things that the speaker considers bad or negative.
2. ~てばかりいる (Doing nothing but... / Always doing...)
Used when the speaker wants to criticize or express annoyance that an action is repeatedly done, or someone is constantly in that state ("Doing nothing else but ~").
*Cannot be replaced with だけ (only) or のみ (only).
3. ~ばかりでなく (Not only... but also...)
Vる / Vた / Vない + ばかりでなく...(も)
Used in the pattern "X ばかりでなく Y も" to express "Not only X, of course, but also Y".
* Besides the particle も, you can also use 「まで, さえ」 in the latter clause. In spoken language, 「だけじゃなくて」 is more commonly used.
4. ~ばかりだ (Keep doing... / Just waiting to...)
This pattern has 2 completely different meanings depending on the accompanying verb and context.
Expresses a change that only follows a bad (negative) trend. Can be replaced with 「...する一方だ」. The preceding verb is usually a verb of change like 弱くなる (get weaker), 悪くなる (get worse), 減る (decrease)...
Expresses the meaning that "Everything is prepared, and it is in a state where the next action can be taken at any time."
5. ~たばかりだ (Have just...)
Expresses that an action or event has just happened or just finished relative to the time of speaking (even if the actual time passed varies, it could be a week, a month, or even a few years based on the speaker's perception).