You're definitely not alone! I really think if we were more honest then we'd realise nearly every mother feels like this. I certainly do. I have 2 boys age 6 and 2. I feel so worn down by the sheer monotony and relentlessness of it all. I love them both enormously. I'd never be without them but it's like a job that's just never done. The same shit needs doing, day in, day out and it's just exhausting.
Both my boys are relatively easy going now but the simmering squabbles and endless questions, bed times, cooking, cleaning, picking up the same crap every day gets to me. So no, you're definitely not alone!
One thing that has made my life better is trying to congratulate myself on the boys being fed, dressed, clean (ish!) and loved every night when I put them to bed. Their bellies are full and we all make sure we kiss each other and tell them we love them. Sounds cheesy but as long as kids feel loved then I really do think you're doing a good job.
Also try to make time for yourself. Certainly not easy with a 7 month old but believe me it is important just once a week to take some time out to either meet up with friends, go for a walk, go shopping, whatever floats your boat. I go swimming once a week and make time in the evenings to read and do things I enjoy!
It does get better as they get older, that's all I can say. I was miserable when they were babies but it gets so much more interesting as they get older.