So you are doing some things right. You don't have individual line-items that are massively out of whack. You budget off 4 weeks so you have extra left.
But I would suggest a few changes in the way you think about money. E.g., the things you spend the craft fair money and the extra 4 paychecks are not "extras" -- they are, in fact, expenses that you need to plan for. They're not really optional, are they? I mean, you're not going to forego the wedding or the birthday party or the dental work, right? These are things you plan to do, so you should plan that spending into your monthly budget. I mean, it's not a surprise that birthdays come every year, right?
Yeah, ok, sure, you may not need massive dental work every year -- I hope! -- but you can still pretty much count on a kid to break an arm or get the flu or whatever. The key is not to get caught up on the details, but set up categories like "medical" and "gifts" and "travel," so that you are setting aside money every month, in advance. So when stuff like that comes up, you're not taken by surprise -- you've already got it sitting there. For you, I'd actually recommend You Need a Budget -- it forces you to budget in advance like this. And that kind of detailed tracking will give you much more insight into where the money actually goes.
And this planning needs to include savings -- off the top, not with what's leftover. Period. Just as non-negotiable as tithing. Pay God first, sure, but then pay yourself second. Don't let current you shortchange future you.
The other thing is I notice that you are paid weekly but have the tithing set monthly. Is this "real" or is it an artifact of the spreadsheet? If you actually pay over 10% every week after your paycheck comes in, you can ignore this -- but if you are making a monthly contribution of $485 each month, this is going to make things extra tight in the 4-paycheck months. It might smooth the ride a bit if you do the tithing based on the amount you actually have in-hand every month.
Also, what's Liberty?
Otherwise, Verizon is ridiculous; groceries/takeout/sundries (almost $400) also may be able to be trimmed a bit; and perhaps some of the baby stuff as well; you're also doing the right thing with tackling the ductwork and trimming where you can. But, yeah, you can't make money magically appear where there is none. If your plan is to live off of 90% of a single less-than-$60K income, and live in a home that is close to work in Philly, then yes, you're not going to have a lot left over for other stuff.
To put it another way: you have many, many options for bringing more breathing room into your budget -- your wife could work a regular job; you could live farther and commute; you could stop tithing; etc. In effect, you have chosen to "spend" the foregone money on living according to your values -- the "luxuries" of a short commute and a SAHM. And I think that is a good thing -- to my mind, living according to your values is more important than more "stuff" anyway.
I know, not that that makes it any easier when you always feel so tight. But it helps me to remind myself that I do have choices -- that I am living the life I am because it suits my values and priorities and family, and that the tradeoffs are sacrifices I willingly make for those more-important goals. And if my lifestyle no longer suits, then I can just as easily make a different choice and trade one set of benefits and burdens for another. FWIW.