How to succeed as EM when I never had a manager

I recently joined a startup with fairly big engineering team. I always worked in startup so lacked mentoring and find myself very difficult to cope with people and tech problems at the same time.

I feel people are losing trust in me as my personality is on the serious side. I don't feel accepted and also work load is quite high.

I want to succeed here but the challenges are so many and I constantly feels overwhelmed.

Few challenges:

1. The team is big and I have direct reporting of nearly 25 memebers
2. There is no process in the team and enforcing any process requires a lot of effort and resistance from team
3. There is no prior experience in people management so I don't realise when things are getting forceful.
4. I am going a lot in personal life so the stress sometimes affects professional space.

I don't know how to handle current situation. I get advise from people but the workload is so high that I am unable to find time for reflection. Constantly feeling of drain out is making workplace difficult for me.

What can be done by me to be successful here?