Bootstrap weird Margin Behavior in Rows - html

Question

I'm creating a form on my event management system website to allow you to create events. The page is using Bootstrap on the Admin-LTE template.
I have split part of the form into two columns. On the right column is a section to enter the number of spaces on the event and on the left is a section to enter the start and end date and time of the event. I wrote the HTML code for the right side first and am now trying to do the left side, however for some reason the space between the bootstrap rows on the page has changed despite the only different between each side is changing the check box to a number input (I will eventually add a datepicker drop down to this, however the same issue occurred when I tried it previously) and a few others changes in the naming of inputs.
Any suggestions to fix it would be very appreciated!
<div class="box box-primary">
<div class="box-body">
<div class="input-group">
<span class="input-group-addon">Event Title</span>
<input type="text" class="form-control" placeholder="Event Title" id="txtEventTitle">
</div>
<br>
<div class="row">
<div class="col-md-6">
<div class="row">
<div class="col-lg-6">
<div class="input-group">
<span class="input-group-addon">Start Date</span>
<input type="number" class="form-control" placeholder="Start Date" id="dteEStart">
</div>
</div>
<div class="col-lg-6">
<div class="input-group">
<span class="input-group-addon">Start Time</span>
<input type="number" class="form-control" placeholder="Start Time" id="timeEStart">
</div>
</div>
</div>
<div class="row">
<div class="col-lg-6">
<div class="input-group">
<span class="input-group-addon">End Date</span>
<input type="number" class="form-control" placeholder="End Date" id="dteEEnd">
</div>
</div>
<div class="col-lg-6">
<div class="input-group">
<span class="input-group-addon">End Time</span>
<input type="number" class="form-control" placeholder="End Time" id="timeEEnd">
</div>
</div>
</div>
</div>
<div class="col-md-6">
<div class="row">
<div class="col-lg-8">
<div class="input-group">
<span class="input-group-addon">Male Spaces</span>
<input type="number" class="form-control" placeholder="Event Title" id="numEMaleS">
</div>
</div>
<div class="col-lg-4">
<div class="checkbox"><label><input type="checkbox" id="cbxEMaleS">Unlimited Spaces</label></div>
</div>
</div>
<div class="row">
<div class="col-lg-8">
<div class="input-group">
<span class="input-group-addon">Female Spaces</span>
<input type="number" class="form-control" placeholder="Event Title" id="numEFemaleS">
</div>
</div>
<div class="col-lg-4">
<div class="checkbox"><label><input type="checkbox" id="cbxEFemaleS">Unlimited Spaces</label></div>
</div>
</div>
</div>
</div>
</div>
</div>

Answer 1

I've switched the way my rows and columns are organised, so that each side is assigned into a row before the left or right columns and therefore the height of the checkboxes will also affect the left side of the page. I then decided to re-order them so it made a bit more sense.
<div class="row">
<div class="col-md-3">
<div class="input-group">
<span class="input-group-addon">Start Date</span>
<input type="number" class="form-control" placeholder="Start Date" id="dteEStart">
</div>
</div>
<div class="col-md-3">
<div class="input-group">
<span class="input-group-addon">Start Time</span>
<input type="number" class="form-control" placeholder="Start Time" id="timeEStart">
</div>
</div>
<div class="col-md-3">
<div class="input-group">
<span class="input-group-addon">End Date</span>
<input type="number" class="form-control" placeholder="End Date" id="dteEEnd">
</div>
</div>
<div class="col-md-3">
<div class="input-group">
<span class="input-group-addon">End Time</span>
<input type="number" class="form-control" placeholder="End Time" id="timeEEnd">
</div>
</div>
</div>
<br>
<div class="row">
<div class="col-md-4">
<div class="input-group">
<span class="input-group-addon">Male Spaces</span>
<input type="number" class="form-control" placeholder="Event Title" id="numEMaleS">
</div>
</div>
<div class="col-md-2">
<div class="checkbox"><label><input type="checkbox" id="cbxEMaleS">Unlimited Spaces</label></div>
</div>
<div class="col-md-4">
<div class="input-group">
<span class="input-group-addon">Female Spaces</span>
<input type="number" class="form-control" placeholder="Event Title" id="numEFemaleS">
</div>
</div>
<div class="col-md-2">
<div class="checkbox"><label><input type="checkbox" id="cbxEFemaleS">Unlimited Spaces</label></div>
</div>
</div>