Warning: kind of long-winded

My due date is in 6 weeks and I'm struggling (ummm stressing) over a name for our baby boy. DH's first name is William and we always assumed we would name our first boy William and call him Liam. We both have Irish backgrounds so the nickname seemed perfect. However, over the last two years I've become disillusioned with the name because it grew to be so popular, and I now feel like it's sort of lumped in with the trendy "end-of-name nicknames" like Zander, Topher, etc.
After ruling out Liam, we figured we'd stick with William and just call him that (or Will). But, I can't get over wanting a name of Celtic origin. We are both really into Celtic culture and like I said, it's both of our family backgrounds. My husband goes by his Irish middle name and that also makes me want to keep the Celtic names going.
Now we're thinking about choosing a Celtic MN and calling him by that. (I know many people dislike calling by MNs but it's sort of a tradition in DH's family and he likes it). I've loved the name Rowan for a few years now--love the way it sounds and the nickname Rowe. Also love that it's a tree (we're big time nature people) and has a lot of folklore surrounding it... love that it's thought of as a protector (goes well with the meaning of William-- warrior/protector).
Here are my reservations about it:
1. Fear that it will become trendy soon, as Celtic names and surnames are both popular right now. But then again I guess that could happen with ANY Celtic name, and part of me wants to say screw it anyway since we're *actually* from Irish/Scottish families.
2. Fear that it will become more of a girl's name. Again, this could probably happen with anything (since now people name girls Ryan, Blake, and James for crying out loud) but then again, with Rowan being associated with either a surname or a tree, it does lend itself to a more unisex feeling and I could see it going more to girls. I'm just trying to figure out if this is even a big deal to me or not, or if it should be. I personally like it better for a boy and would love it see it stay strong as a boy's name.
Any thoughts? Other suggestions are welcome as well.
Re: Rowan
I think if you love it, you should use it. If people stop using masculine names because some people give their daughters masculine names, we're going to have like, 10 masculine names left.
Rowan was my 'compromise' name, and was within a hair of being the name for my son (my DH had not initially liked the name I suggested until day of at the hospital, which is what we went with). I actually had become attached to it, and was a little bummed I didn't get to use it (at the time). I was also really into the name for the very reasons you are (meaning, nature, tree)
So, obviously, love the name. Think its masculine. And am irritated about it being used on girls. I was also worried that a girl would have the name a year or two before him in school, and thus he would be teased for 'having a girls name', but decided to use it anyway (before my DH surprised me with the ok on my other name choice) because like @bringmemylongswordho said - if we don't claim these boy names for boys, there won't be any left.
The odds are extremely unlikely I'll have more children, but if I do, and its a boy, I intend to choose Rowan.
I say go for it
I think it might get more popular, but I don't think it will ever be Liam popular, or even close. I was also worried about its use on girls and we did end up meeting an older girl in town named Rowan. It bothered me at first but now I don't care. He's a boy and people will get used to it as a boy name as they get to know him.
If our LO is a boy he will be William and I struggle with the nicknames/popularity too. However, it is such a classic name and has family significance so I don't let it bother me too much.
Baby #2 Due 3/7/20
Personally i would just go Rowan fn but if you need to, William Rowan does sound nice depending on what your ln is.
William may not be a 'Celtic' name per say, but it is very popular in the whole British Isles.
I really dig them both honestly.
Are we only worried because we don't want our boys to be associated with anything girlie?
I actually picked out Rowan for my firstborn when I was a girl (Also planned on using Birch, lol) I loved how it sounded unique in a town filled with Ben and Sarah's but it wasn't too outlandish. And whilst I've since started thinking of it as a unisex name, my first impression, to this day is male.
Of course, twenty years later when I start to write my baby's name list and discover Rowan broke the top 20 in the UK at the start of the year, it actually hurt. Kinda like your best friend using your perfect baby name before you do a la Sex and the City. As much as I loved it, I couldn't use it after that.
If you're still taking suggestions, how about another tree? Birch or Oak are strong male names. Ash was popular a while ago but not too recently for it to be common and it's not due for a comeback soon. There are also a load of 'new' tree names like cedar and sequoia.