"J'ai toujours..." (I always have) "J'ai toujours aimé" (I always have loved). Use passé composé et notice that the word always is in between the 2 part of the verb, that's where it belong (NOT before the verb like in English). Also, please note that it's the verb to love (or another verb if you had said for example "I always have been") that we conjugate in French. The "have" bit (like others small particles such: "do", "did", "would") is only to determine witch verb tense to pick. It's not the verb "to do", or "to have". I hope it makes sense to you now!

J'aime quelque chose depuis toujours PS I'm not a native speaker! But I'm pretty sure the present indicative is used!