Suddenly a moany baby, Why?

[Cemkg123]

My daughter is 12 weeks old today. She was breastfed until 6.5weeks then moved to formula (many reasons) since changing to formula she's been great, napping well, can sit in her bouncer, on her playmat and entertain herself for a while (was never able to do this before as she was very VERY clingy) she's so happy smiley all the time, barely cries just moans when she's hungry or bored, soon as the bottle goes to her mouth or I pick her up she stops.
The last 2 days however, she's been pretty grumpy. Hard to keep entertained for longer than 10 mins then starts crying. Find something else to do with her, again 10 mins later she's crying. Obviously she's been fed and nappy changed so it's not that. And it's not just a moany cry, it's a proper cry. I try to comfort her but it's not always working anymore.
I've noticed she contanstly wants to be sucking though, hands are always in her mouth, and it's a very aggressive suck, but she wont take a dummy. Before she would take a dummy for about 10 mins and then spit it out and she's was fine. It was like she just wanted to suck for a bit. But now she won't take it at all. She's been dribbling a bit more than usual but not loads. If I put my finger near her mouth she'll go straight for it and bite down.
Could she be teething?
Or is her real personality starting to come out now? This is what im scared of... I'm a single mum and the first 6 weeks were really difficult because of how needy she was I couldn't get anything done, and then she was perfect after changing to formula and now I'm scared she's going to go back to her old ways. I hope she's just teething.

Also to add... when she's sucking her hands she gets really annoyed because it's like she can't keep them in her mouth. She also tries to suck her thumb which she also hasn't mastered yet. So she gets angry and cries. I try the dummy while she's doing this but makes a face like I've put the most disgusting thing in her mouth and spits it out.

She sounds perfectly normal!

1. Could be a bit of teething or she my have just discovered her hands and how they feel in her mouth. Try giving her tether to chew on.

1. Could she be hungry? Have you tried giving her the bottle if she is getting frustrated with the sucking.

1. She is going through developmental leap 3. I'd really recommend getting the wonder weeks app as it's so handy when they suddenly start being grumpy to know that is the cause. I've attached a screen shot of the signs she is in the leap. The good news is it ends soon!

Which formula is she on OP? There have been a lot of threads recently about Vow & Gate a Altamira where the babies are inconsolable on their new formula. If it’s either if these you are using, I’d swap and see if her mood improves

Sounds like teething to me.

Only thing I'd add to previous comments OP is just worth keeping an eye on things like her temperature and how much she's drinking. My little girl got a urine infection at 10 weeks old and only symptoms were sudden increase in crying, a temperature spike and reduction in milk. Obviously this is pretty unlikely but just mentioning just in case as I didn't even think to take her temp until someone suggested it (despite this being my second)