Every 3 months is not too long. It's the right amount of time for YOU so it's what you should do. Please try to stop caring so much about what other people want or say or think of you. And start caring more about what you want and think.
PS I see some of my in-laws once or twice a month because I really like them and they're respectful and we get along. That's honestly really frequently for me to see anyone aside from my husband, kids and very best friends... we have a very busy life with 4 kids and I work full time, own my own business and have my own interests/hobbies (mainly working out at weightlifting classes and doing Zumba, plus a book club, writing club and my kids' activities and things I like to do with them on a regular basis), so I honestly couldn't fit in seeing them any more than this... sometimes I don't even see them once a month and that's fine, we still love each other but life just gets busy!
I have other in-laws I rarely see... maybe twice a year on their birthday and a get together around the holidays but not ON the holidays because we do Christmas day with our immediate family (me, my husband and our kids) only, since we only get so few of them and want to relax and enjoy them and not rush around everywhere else or hosting other people, etc. That's because I don't particularly like those in-laws and/or they don't particularly like me, and that's fine... not everyone can be expected to get along with everyone else, and I don't want to waste precious time being fake or spending time with people I find dreadful or just boring, etc.
Sometimes my husband and/or kids see some of those in-laws more than I do, if he goes to see them without me. Sometimes they watch our kids for us. It all depends on who they are. If they are disrespectful a-holes then neither of us see them and they certainly don't see our kids as we don't want them brought up normalizing being disrespectful a-holes or witnessing unnecessary fights or drama or alcoholism which runs rampant in both my husband's and my families, etc. (Husband does have a couple uncles I consider disrespectful a-holes and who may be alcoholics to boot, who he sees more than I or the kids ever do, in that he goes skiing with them maybe once or twice a year and might help them work on a car or fix an appliance or they help him do the same, one or two more times a year, and it's fine with me that he sees them since he's his own person and I don't try to control where he goes or who he sees. But our kids do not go around them other than maybe at a big family get-together on the 4th of July or around Christmas, and if those particular uncles show up then we usually greet them nicely, exchange gifts or pleasantries, and then keep our distance and either leave early or prepare to leave early if necessary, as those are the ones who are most prone to drink too much or start drama or be rude, etc., and I don't generally like being around them. They've aged poorly due to bad habits so can't be at many family functions nowadays, which is a good thing for everyone else, IMO.
And my own parents? We see them on the 12th of Never because they are incapable of being civil or respectful and are always causing drama or making rude, judgmental, disparaging remarks or being verbally, emotionally and even physically abusive to each other and/or us and/or various other people who are around, or my dad drinks and my mom gets mad at him for it yet also blames it on all of the rest of us and/or expects us not to say anything or be upset about it ourselves and to pretend like everything is normal and fine and great, and to walk on eggshells around them lest we say something to set off my dad's temper and hurt my mom's ever-fragile little feelers, etc. etc. etc. I don't have enough space on the Internet or in my head to rehash all the many ways they have been inappropriate to have our kids or ourselves around, so I finally cut them off nearly two years ago or so now, and so I never, ever see them and have never been happier. :)
I'm telling you all of this because it really is up to YOU and what YOU want, and the sooner you start living your life for yourself instead of for everyone else, the happier I know you'll be, even though I also know it's hard at first because I used to try to keep relationships going with people who didn't really give a flying fig about me, or who I actually didn't really like much when I really thought about it, and it was exhausting! Through therapy I've been able to decide what I really want to do with my precious time and who I really want to spend it around, and to rid myself of the feelings of guilt or obligation that society puts on people, especially women/wives/mothers, to carry on such mentally and physically exhausting relationships.