I was dating this guy for about a month. Within that,He convinced me to let my bird stay with him and he, my dad, and I all agreed that I would get her back if we broke up. Texted him last night and he’s refusing to give her to me and says I can come see her. If I take her without using physical force(unless needed) would I get in any sort of trouble with the law?
You don't state a jurisdiction, but the following will apply in most common-law jurisdictions.
If you entered with permission, picked up the bird and walked out with it without any objections then a charge of theft would not stick; you were simply reclaiming your own property with the permission of the householder.
However from your post that doesn't sound likely. If your ex objects to you taking the bird then they can call the police. The police will refuse to get involved in arguments about ownership and will just act to preserve the status quo ante. As long as you haven't broken in or acted deceitfully then you haven't committed a crime, but they are unlikely to let you take the bird as long as the person with possession claims legal title.
If you try to "steal it back" then you will be guilty of theft, and possibly burglary, criminal damage and maybe other crimes depending on how you did it. Don't go there.
You probably need to file some kind of civil case for the return of your property. Details will depend on the jurisdiction, but if you can get a court order for possession then the police should accept that as evidence that you are acting legally when you turn up to reclaim your property. However (again, depending on jurisdiction) you might need to hire a specialist to do the actual repossession; the laws about gaining entry, searching property etc tend to be complicated and you don't want to get on the wrong side of them.
This is all on the assumption that the value of the bird is lower than the likely cost of hiring a lawyer. If this is an expensive bird then you need legal advice.