2 year old has become aggressive

[Ralocon]

Hi everyone.
I'm very new to these threads and have never actually reached out for help in this way before but I'm completely desperate.
I have 2 beautiful toddlers. A 2 year old boy and a 1 year old girl. My boy is not talking yet. He is very bright, understands most commands and is generally very engaging. Over the last few months he has become progressively more aggressive with my DD. He sporadically attacks her. Out of nowhere he will lunge at her and viciously bite her or rugby tackle her to the floor. His biting is also often directed and myself, his dad and his Nanny. During these episodes I can clearly see the intent in his face. He protrudes his bottom jaw and his eyes widen.
We've tried to identify triggers but it's happening so randomly we havent been successful. I've read every article there is and tried to implement all of the recommended tactics but nothing is having even a small impact.
DS is a covid era baby. He hasn't had an opportunity to appropriately socialize outside of the house. Hes been on waiting lists for 8 creches for 10 months now are there are no places available. I have often taken him to play groups and messy play etc and he doesnt exhibit any of this behaviour towards other children thankfully .
We both work full time (3 days at home 2 in the office) so my mother takes care of them in our house every day. Shes at a point now where shes just not able to manage him. He refuses to allow us dress or change him without an almighty battle and hes hurt her on more than a few occassions.
He can be so beautifully behaved at times too. He loves to help out with chores and loves nothing more than to dance or sing along with me. The fact that he cant speak yet makes all of this so hard because he cant communicate his feelings. I feel like such a terrible mammy. My poor DS adores him but at the moments he is a serious risk to her safety. Separating them is just not realistic so they need to be supervised closely 100% of the time.
Am I doing something wrong? We celebrate every single good behaviour and shower him with affection all of the time.
If anyone has dealt with something similar I'd really love to hear from you. I've spent the last month crying every evening after they go to sleep because I'm so overwhelmed and worn out xx

This feels so hard :( I have a similar age gap (boy-girl) and whilst nowhere near your level, the older one is also deliberately hurting the younger one (to the point the younger one is now doing the same in the nursery, hooray... :/ )

I can tell he is more so when tired and hungry, have you eliminated these? Other than that maybe he feels just frustrated with his communication. As far as I can tell all we can do is remove him from the situation, calm him down in any way he prefers and show him the correct way to treat his sister. And repeat. I am doing this and it is not working but I am not giving up just yet.

Last option would be a nanny for him for a few hours a day, an au-pair or something similar, or an alternative childcare for a bit to separate the kids and give him a bit more one to one attention (and give your baby girl a break too). Hope someone more knowledgable comes along with better advice soon.

I suspect it's also frustration about communication and not being able to speak. I think the previous advice is spot on so I would follow that but it's not going to be a quick win. I'm sure you are already but lots of reading together and narrating your every move to support his speech development too.

Could also be lack of control frustration too. Have you tried giving him a choice of two socks, pants, teeshirts etc when getting dressed? You could extend it to snacks and drinks too - even giving them control over tiny decisions seemed to really help with mine. Sarah Ockwell Smith's Gentle Parenting book I found really good but it's definitely a long haul approach, rather than overnight miracle.

I would also make sure he's getting some one on one time with you every day without the smaller one. Could be just 20 minutes and whatever he enjoys doing.

If he is 2.5 years, he could start a few mornings at preschool which would give your Mum and your smaller person a bit of a break. Other than that I would second the suggestion of a nanny for him even just two mornings a week.

Really appreciate that feedback. Thanks so much. Unfortunately childcare places in my area are non existent. He is enrolled for Montessori this Sept though. He'll attend for 3 hours 3 days a week so hopefully that will shift things in a more positive direction.
Following my mini breakdown the other day (and by mini I mean massive!!!) I contacted every private speech therapist in Leinster and I've managed to get an appointment for early July. He had been referred by the PHN but the current lead time in my area is averaging at 3 years. Seriously like!!!
I'm trying to view the world through his little eyes and I really feel like the speech delay is the root cause of all of this. He's bursting to communicate but the words just wont come. I actually have an appointment with thr PHN tomorrow for his 2 year check so I have a list of things to chat to her about.