Lots of guys run into this issue early on, but not many of us have the problem for long. It all depends on your dosage (and we don't talk about dosages in threads) and genetics. Also the delivery method seems to matter; guys on gel and cream seem to take longer. At three months, I'd say it's too soon to genuinely worry.
I checked my old journal. At just under two months of injecting the so-called full dose, I had significant changes in my voice, but I think a lot of other people hadn't noticed yet. So I guess they weren't all that significant! At about two months, it went considerably deeper, but I don't know how many people noticed. At three months, I was deeper still, but not yet in a distinctly male register. My voice started seriously cracking at four months in--I think that's when I really started achieving a male tenor. The cracking went on for quite some time after I slipped into tenor range.
I went along like this, occasionally going a bit lower and achieving a bit more resonance, for quite some time. Then, more than a year in (maybe 17 months?), I suddenly wound up in baritone range. I've been fairly stable since then, and I've been on T for nearly three years.
Hang in there, and try to be patient. And if you're on a smaller dose (you can PM me about that once you reach 15 posts), it will take a bit longer than it would have otherwise.