D.M.
I have worked full-time and part-time while being a mom to my two kids (now 3 and 20 mos). It is challenging to try to balance it all - children, spouse, work, home, friends, and time for you!!!
A friend gave me great advice - "whatever you are doing at the time, do the best you can". Since you can't be two places at once, focus on the present moment. Simple advice, hard to totally embrace. I relate to feeling like you are doing nothing "well".
Likely, you are doing better at all than you think, but you are exhausted... for good reason. Two part time jobs are tough to balance. Can you do just one? That would be my main advice on your post - it may give you some relief. Also, don't be too hard on yourself, it is still early and you will adjust. Give yourself permission to find out what you need and adjust accordingly.
Take Good Care!