I went back to work when DS was 10 months and I was so ready to go back. I loved DS, obviously, but I was going crazy being at home all day every day.
My job is full time over three days which is perfect as although I don't really see DS on the days I work (I only see him for 30 minutes in the morning) it means I get four full days a week with him. I feel like I have the best of both worlds.
One of my shifts is always on either a Saturday or Sunday so DS is with DH but on the other two days a week he goes to a childminder who is fantastic.
My first week back at work was really hard as it was Mon-Fri 9-5 as I was doing lots of compulsory training before I could go on to normal shifts and I hardly saw DS. By the time I got home each evening I only saw him for about 45 minutes before I had to put him to bed. For that first week there were a lot of tears. I would cry on my way to work and find myself crying after I had put him to bed.
He took his first steps at the childminder's house but I'm not too concerned about that. I could have missed his first steps even if I had have been a SAHM, he could have been with DH, MIL or anyone, who knows. Unless you are glued to your child 100% of the time there's no guarantee you will see the first steps anyway. In the grand scheme of things it doesn't really matter. DS had been walking for 5 months now, I saw his "second steps" and the million and one steps he has taken since then and I'm happy with that 
I really live my job, I have been back at work for 5 months now, but I still have the odd day every few weeks where I really wish I didn't have to leave him. Nothing upsets me more than when he's poorly or had a bad night and I'm walking away from him to go to work.
However, as a result of me working we are able to give DS a much better life. We have money to take him to nice places, we can afford two holidays abroad every year, we have a good savings account and we put £75 each month into DS's bank account. If I didn't work we couldn't do any of that.
If me and DH really wanted to we'd probably be able to live off just his wage and me be a SAHM but we both think the benefits of me working outweigh the benefits of SAHP'hood in our particular circumstances.
My advice to you is take the job, give yourself a few months to settle into it whilst you work out how to juggle your job and your baby and then decide if it is working for you or not.