Well first there is nothing wrong with Sahara Bermuda grass. It is better to use a blend, but don't sweat it yet.

When did you plant it last year? Did it come up and fill in?

Right now is the perfect time in Dallas for the first application, so you did good there. I suspect you just have the normal winter annuals although a lot of clover can indicate low soil nitrogen.

Bermuda is just now starting to good and green right now, wait a couple of weeks to give the fertilizer a chance and th etemps to warm up a bit. Everything is late this year with our very long and bitter cold winter we had.

I would hit it hard with some 2,4-d in a week or two, that should wipe out the clover. You can get 1 to 2.5 gallons of concentrated 2,4-d at tractor supply, twenty to fifty bucks, depending on the size. Then get a dial sprayer and apply. Use gloves, googles and protective equiptment (long sleves and pants, rubber boots). You dont want a heavy exposure of this stuff.
This is the most common active ingredient of all weed killers, with a very few exceptions.

Sounds like your planting was normal for that time of year. Planting Bermuda seed that late is not recommended. Bermuda planted late in the season does not survive as well as if it has been planted in the spring. Like TW said this has been a bad winter in your area and mine. My Sahara Bermuda is coming back but it is much slower than usual because of the cold. I like Sahara Bermuda and use it in my 3 acre yard. I have a friend/neighbor that recently built on 5 acres. Right now I have prepped about 2 acres of the yard and am close to planting Sahara Bermuda there. The temps are getting close to perfect and I hope rain continues to fall often enough to help germination along.
botanicalbill is correct about the herbicide. I had to do this several years before I got rid of the undesirable weeds and grass. Additionally,if you have an invasion of Bahia grass you may need to spray with DuPont's Cimarron-plus. Correctly used herbicides will not hurt the Bermuda permanently even when just planted that season. Studies at several universities proved that myth to be wrong. Good luck. Remember a good lawn takes patience and consistent care.
It is possible that you may need to overseed or start over as well but I'm thinking some of what you planted will come back soon. Planting now would yield better results than a late season planting.

TW wrote: "Well first there is nothing wrong with Sahara Bermuda grass. It is better to use a blend, but don't sweat it yet."

Just curious, buy what's the reasoning behind using a blend instead of one specific type of seed? Wouldn't you want the grass to match? Thanks.

Because one of the blends will grow faster and dominate the the others. Presumably, it'll be the one that grows best for your area.

It's a way of hedging your bets, so to speak.

I planted in mid August. I mowed it 2x and then put down some fertilizer to get it going. It was very patchy and didn't fill in very much, but it seemed like it was growing vertically, but not spreading, as I had to cut it with my reel mower 2x per week. I have one spot that is probably 4 feet x 4 feet where nothing grew at all. The soil didn't seem compacted or anything, so I am not sure what the problem is there.

Is it possible to overseed with a blend later in the year?

Overseed now if you are planting Bermuda. Bermuda planting is not recommended in late season because the immature plant does not survive the winter cold as well as a more mature plant.

I would wait. I think that in 30 days you will be at least humored over your worries. You have until August to overseed bermuda.